ci: upgrade pytest for requests framework test (#9362)

Avoids these kind of errors in the CI:
https://github.com/DataDog/dd-trace-py/actions/runs/9204318180/job/25317642591?pr=9344#step:8:62

## Checklist

- [x] Change(s) are motivated and described in the PR description
- [x] Testing strategy is described if automated tests are not included
in the PR
- [x] Risks are described (performance impact, potential for breakage,
maintainability)
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed or label `changelog/no-changelog` is set
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/))
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))
- [x] If this PR changes the public interface, I've notified
`@DataDog/apm-tees`.

## Reviewer Checklist

- [x] Title is accurate
- [x] All changes are related to the pull request's stated goal
- [x] Description motivates each change
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- [x] Testing strategy adequately addresses listed risks
- [x] Change is maintainable (easy to change, telemetry, documentation)
- [x] Release note makes sense to a user of the library
- [x] Author has acknowledged and discussed the performance implications
of this PR as reported in the benchmarks PR comment
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Co-authored-by: Emmett Butler <723615+emmettbutler@users.noreply.github.com>

.github/workflows/test_frameworks.yml

@@ -675,6 +675,9 @@ jobs:
       - name: MarkupSafe fix
         if: needs.needs-run.outputs.outcome == 'success'
         run: pip install --upgrade MarkupSafe==2.0.1
+      - name: Pytest fix
+        if: needs.needs-run.outputs.outcome == 'success'
+        run: pip install --upgrade pytest==5.4.3
       - name: Run tests
         if: needs.needs-run.outputs.outcome == 'success'
         run: PYTHONPATH=../ddtrace/tests/debugging/exploration/ ddtrace-run pytest -p no:warnings tests