ci(python-deps): update transformers version constraints in tox (apache#36506)

* ci(python-deps): update transformers version constraints and test command

Add python version-specific constraints for transformers package to avoid union type syntax issues. Also include transformers version check in test command for debugging purposes.

* ci(workflow): increase timeout for python dependency tests

The previous timeout of 180 minutes was insufficient for some test runs, so it was doubled to 360 minutes to prevent premature job termination

Author: liferoad

.github/trigger_files/beam_PostCommit_Python_Dependency.json

@@ -1,4 +1,4 @@
 {
     "comment": "Modify this file in a trivial way to cause this test suite to run",
-    "modification": 2
+    "modification": 3
   }

.github/workflows/beam_PostCommit_Python_Dependency.yml

@@ -60,7 +60,7 @@ jobs:
         job_name: ['beam_PostCommit_Python_Dependency']
         job_phrase: ['Run Python PostCommit Dependency']
         python_version: ['3.9','3.13']
-    timeout-minutes: 180
+    timeout-minutes: 360
     if: |
       github.event_name == 'workflow_dispatch' ||
       github.event_name == 'pull_request_target' ||

sdks/python/tox.ini

@@ -557,12 +557,16 @@ commands =
 deps =
   sentence-transformers==3.3.1
   accelerate>=1.6.0
+  # Use Python version-specific transformers constraints to avoid union type syntax issues
+  transformers>=4.28.0,<4.55.0; python_version < "3.10"
+  transformers>=4.28.0,<4.56.0; python_version >= "3.10"
 passenv = HF_INFERENCE_TOKEN
 extras = test,gcp
 commands =
   # Log aiplatform and its dependencies version for debugging
   /bin/sh -c "pip freeze | grep -E sentence-transformers"
   /bin/sh -c "pip freeze | grep -E google-cloud-aiplatform"
+  /bin/sh -c "pip freeze | grep -E transformers"
   # Allow exit code 5 (no tests run) so that we can run this command safely on arbitrary subdirectories.
   /bin/sh -c 'pytest apache_beam/ml/transforms/embeddings -o junit_suite_name={envname} --junitxml=pytest_{envname}.xml -n 6 {posargs}; ret=$?; [ $ret = 5 ] && exit 0 || exit $ret'