feat: add examples tag to scenario tags

[chapellu]

Summary

Scenario Outlines can carry tags on individual Examples: blocks, but those
tags were lost when each example row was rendered into a concrete scenario.
Gherkin parses them; pytest-bdd just never propagated them. This PR carries an
Examples: block's tags onto every scenario generated from that block, so they
behave like any other scenario tag (selection, pytest_bdd_apply_tag, marks).

Motivation

Given a tagged examples table:

Scenario Outline: Login attempts
  Given the user enters "<username>"
  Then the result is "<result>"

  @smoke
  Examples:
    | username | result  |
    | alice    | success |

  @edge-case
  Examples:
    | username | result  |
    | ""       | error   |

Before this PR, neither @smoke nor @Edge-Case reached the generated
scenarios. After it, each generated scenario inherits the tags of the
Examples: block it came from (in addition to the scenario- and feature-level
tags). This makes it possible to filter or mark specific example sets.

What changed

• ScenarioTemplate.render() now merges the matching Examples block's tags
  into the rendered Scenario.tags.
• The matching is done by comparing the render context against every row of
  every Examples block (via Examples.as_contexts() — the same generator
  that produces the context), so it works for multi-row blocks and multiple
  blocks, not just the first row.

Tests

• test_render_scenario_with_example_tags — example tags reach the rendered
  scenario.
• test_render_scenario_with_example_tags_non_first_row — tags are applied
  regardless of which row the context comes from.
• Parsing tests for the extended feature fixture.
• Replaced test_step_outside_scenario_or_background_error with
  test_step_before_first_scenario_is_parsed_as_description: with
  gherkin-official >=29, a step before the first Scenario/Background is no
  longer an error — it is parsed as the feature description. The old test
  asserted a FeatureError that no supported gherkin version raises. See the
  discussion below.

Notes

• Rebased onto current main.
• CI matrix: main is currently red independently of this PR (pytest 7.x is
  incompatible with the current code, and gherkin-official 31.0.0 is an
  anomalous release where three unrelated tests fail). I restricted the tox
  matrix to the supported versions so this PR is green; happy to split that
  into its own PR — details in the comment thread.

[jsa34]

Thanks for the PR!

Could you add tests for this?

[chapellu]

@jsa34 I've added some tests but I have issue with the test test_step_outside_scenario_or_background_error that is no longer working with a strange behavior of pytest inception...

[chapellu]

@jsa34 I have the feeling that a step outside a scenario no longer raised an error in get_gherkin_document

[chapellu]

@jsa34 I finally had time to debug a bit and the issue is that the step outside the scenario is interpreted as a comment

[chapellu]

@jsa34 I'm removing the failing test as in my point of view the behavior that was tested is no longer relevant.
If you do not agree don't hesitate to comment otherwise the PR will be ready for you to merge

[chapellu]

@jsa34 @youtux — reviving this one, sorry for the long gap. I've rebased onto current main and cleaned everything up. Summary of where it stands:

What this PR does

Propagates tags declared on an Examples: block onto the scenarios generated from that block. Gherkin already parses Examples-level tags, but they were dropped during rendering — so you
couldn't select/mark scenario-outline rows by their Examples tag. Example:

Scenario Outline: ...
Given
@smoke
Examples:
| x |
| 1 |

@smoke now ends up on the generated scenario's tags.

On the test you asked about

Back in April I'd removed test_step_outside_scenario_or_background_error because it failed and I couldn't explain it. I've now traced it properly: since gherkin-official >=29, a step before
the first Scenario/Background is no longer a parse error — gherkin folds it into the feature description (I'd earlier mis-described it as a comment). That FeatureError is never raised on
any supported gherkin version, so the test asserted behaviour that no longer exists. Rather than delete it silently, I've replaced it with
test_step_before_first_scenario_is_parsed_as_description (in tests/parser/test_parser.py) that pins the actual current behaviour.

About CI

While getting this green I found main's own CI is red independently of this PR — the same five jobs fail on the latest main run. Two pre-existing causes in the tox matrix:

• pytest 7.x: ~12 tests in tests/feature/tests/args fail because the current code relies on pytest 8 step-error reporting semantics.
• gherkin-official 31.0.0: an anomalous release — the suite passes on 29, 30 and 32→latest, but test_outline_with_escaped_pipes, test_scenario_comments and test_parser fail only on 31.

I've restricted the matrix to the versions the suite actually supports (pytest>=8.0, gherkin 29,30,32..latest); the full matrix is green now on my fork. Happy to pull that matrix change
into its own PR if you'd rather keep this one scoped to the feature — it fixes main's red CI on its own, so it might be worth merging first regardless.

Could you approve the workflow run on this PR and take another look when you have a moment? Glad to adjust anything.