Tox docs build fails in release branches

[aabmass]

Because we do not have a way to override the specific branch in docs-requirements:

opentelemetry-python-contrib/docs-requirements.txt

Lines 7 to 10 in 5c5fc73

	-e "git+https://github.com/open-telemetry/opentelemetry-python.git#egg=opentelemetry-api&subdirectory=opentelemetry-api"
	-e "git+https://github.com/open-telemetry/opentelemetry-python.git#egg=opentelemetry-semantic-conventions&subdirectory=opentelemetry-semantic-conventions"
	-e "git+https://github.com/open-telemetry/opentelemetry-python.git#egg=opentelemetry-sdk&subdirectory=opentelemetry-sdk"
	-e "git+https://github.com/open-telemetry/opentelemetry-python-contrib.git#egg=opentelemetry-util-http&subdirectory=util/opentelemetry-util-http"

This causes dependency conflict in semantic-conventions package, for example this workflow run from #3016:

The conflict is caused by:
    The user requested opentelemetry-semantic-conventions 0.50b0.dev0 (from git+https://github.com/open-telemetry/opentelemetry-python.git#egg=opentelemetry-semantic-conventions&subdirectory=opentelemetry-semantic-conventions)
    opentelemetry-sdk 1.29.0.dev0 depends on opentelemetry-semantic-conventions==0.50b0.dev
    opentelemetry-instrumentation 0.49b1 depends on opentelemetry-semantic-conventions==0.49b1

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip to attempt to solve the dependency conflict

docs: exit 1 (20.20 seconds) /home/runner/work/opentelemetry-python-contrib/opentelemetry-python-contrib> python -I -m pip install pytest -r /home/runner/work/opentelemetry-python-contrib/opentelemetry-python-contrib/docs-requirements.txt -c /home/runner/work/opentelemetry-python-contrib/opentelemetry-python-contrib/dev-requirements.txt pid=1748
  docs: FAIL code 1 (20.64 seconds)
  evaluation failed :( (21.99 seconds)

[emdneto]

@aabmass In 1.29.0 release we didn't have any issues with docs CI because we are skipping it for opentelemetrybot 😅 but I opened a test PR to validate everything is working as expected. I think we won't have problems anymore after #3039, so if you're good with the results, we can close the issue ✌🏻

[aabmass]

Awesome thank you!