Add python 3.14 release candidate to pylib pipeline

Summary

Added a test stage with a python 3.14-rc image to the pipeline.
Part of #216 (closed)

Check List for the Author

• All automated tests pass
• Reference related issues
• Appropriate user and developer documentation (or not necessary)
• Annotations in code (Gitlab comments)

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• Appropriate user and developer documentation (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

.gitlab-ci.yml

@@ -101,13 +101,26 @@ unittest_py3.12:
   script: *python_test_script
 
 unittest_py3.13:
-  allow_failure: true
   tags: [ docker ]
   stage: test
   needs: [ ]
   image: python:3.13
   script: *python_test_script
 
+unittest_py3.14:
+  allow_failure: true   # remove on release
+  tags: [ docker ]
+  stage: test
+  needs: [ ]
+  image: python:3.14-rc
+  script:               # replace by '*python_test_script' on release
+    # Install cargo manually, source its env, and set it to accept 3.14 as interpreter
+    - curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+    - . "$HOME/.cargo/env"
+    - export PYO3_USE_ABI3_FORWARD_COMPATIBILITY=1
+    # Continue normally
+    - *python_test_script
+
 # Trigger building of server image and integration tests
 trigger_build:
   stage: deploy