python: enable payment event tests

[florentinl]

Motivation

Enabling tests is good !

Changes

• Add stripe sdk dependency (covering last 3 major versions across the different weblogs)
• Implement missing routes

Workflow

1. ⚠️ Create your PR as draft ⚠️
2. Work on you PR until the CI passes
3. Mark it as ready for review
   • Test logic is modified? -> Get a review from RFC owner.
   • Framework is modified, or non obvious usage of it -> get a review from R&P team

🚀 Once your PR is reviewed and the CI green, you can merge it!

🛟 #apm-shared-testing 🛟

Reviewer checklist

• Anything but tests/ or manifests/ is modified ? I have the approval from R&P team
• A docker base image is modified?
  • the relevant build-XXX-image label is present
• A scenario is added, removed or renamed?
  • Get a review from R&P team

[github-actions]

CODEOWNERS have been resolved as:

manifests/python.yml                                                    @DataDog/apm-python @DataDog/asm-python
utils/build/docker/python/django/app/urls.py                            @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/django/requirements-django-poc.txt            @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/django/requirements-django-py3.13.txt         @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/django/requirements-python3.12.txt            @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/fastapi/main.py                               @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/fastapi/requirements-fastapi.txt              @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/flask/app.py                                  @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/flask/requirements-flask-poc.txt              @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core
utils/build/docker/python/flask/requirements-uwsgi-poc.txt              @DataDog/apm-python @DataDog/asm-python @DataDog/system-tests-core