test: Add pytest-rerunfailures for integration tests

[vdusek]

Add pytest-rerunfailures as a dev dependency and configure all integration tests to rerun up to 3 times on failure automatically. This helps handle occasional platform-related instabilities without manual test reruns.

Uses pytest_collection_modifyitems hook to apply the flaky marker to all integration tests, avoiding the need to decorate each test individually.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.90%. Comparing base (675eaf7) to head (24e3136).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #746      +/-   ##
==========================================
- Coverage   81.98%   81.90%   -0.08%     
==========================================
  Files          46       46              
  Lines        2681     2681              
==========================================
- Hits         2198     2196       -2     
- Misses        483      485       +2     

Flag	Coverage Δ
integration	56.13% <ø> (ø)
unit	67.84% <ø> (-0.08%)	⬇️

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[Pijukatel]

I would prefer to apply any retries only on per-test basis. Most often I feel that the flakiness is due to specific test design or sometimes it actually exposes real issue. Such blanket retry could lead to hiding issues.

Can you please link some example failures you want to deal with this?

[vdusek]

I would prefer to apply any retries only on per-test basis. Most often I feel that the flakiness is due to specific test design > or sometimes it actually exposes real issue. Such blanket retry could lead to hiding issues.

Can you please link some example failures you want to deal with this?

All tests can fail if the platform is overloaded (or due to similar transient issues). For example:

Coverage XML written to file coverage-integration.xml
=========================== short test summary info ============================
FAILED tests/integration/actor/test_crawlers_with_storages.py::test_actor_on_platform_max_request_retries - AssertionError: assert <ActorJobStat...: 'TIMED-OUT'> == 'SUCCEEDED'
  
  - SUCCEEDED
  + TIMED-OUT
================== 1 failed, 140 passed in 804.50s (0:13:24) ===================
Error: Process completed with exit code 1.

This run failed because the Actor just timed out (rather than because of a test-specific issue):
https://github.com/apify/apify-sdk-python/actions/runs/21358210249/job/61470616028?pr=747

When this happens, the only option is to restart the entire test suite, not just the single test that failed due to the timeout (which means 10+ minutes).