ci: upgrade pytest version used in tests [backport 2.21]

[github-actions[bot]]

Backport 4e8a947fbd2de74fc0fd29a916da1ddfd5adbf49 from #13456 to 2.21.

Fixes test failures in the flask suite by upgrading away from an unsupported pytest version

Checklist

• [x] PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• [x] Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[pr-commenter[bot]]

Benchmarks

Benchmark execution time: 2025-06-23 19:54:36

Comparing candidate commit 94da4087790a34343de1c526f933a9b3e34a47fe in PR branch backport-13456-to-2.21 with baseline commit 89e8597a02cb00bb1b11e0036817dd5a1fdc4662 in branch 2.21.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 344 metrics, 2 unstable metrics.

[github-actions[bot]]

CODEOWNERS have been resolved as:

lib-injection/sources/min_compatible_versions.csv                       @DataDog/apm-core-python
min_compatible_versions.csv                                             @DataDog/apm-core-python
riotfile.py                                                             @DataDog/apm-python
.riot/requirements/1f5205e.txt                                          @DataDog/apm-python
.riot/requirements/f903257.txt                                          @DataDog/apm-python

[github-actions[bot]]

This pull request has been automatically closed after a period of inactivity. After this much time, it will likely be easier to open a new pull request with the same changes than to update this one from the base branch. Please comment or reopen if you think this pull request was closed in error.