Deprecate support for python 2.7 and 3.4 in the next major version

[srprash]

Python 2.7(the last of python2) and 3.4 have reached their end-of-life and are no longer supported.

The SDK should deprecate the support for these versions in the 3.0.0 release. FYI, the OpenTelemetry for Python supports python 3.5 and above.

[michael-k]

Python 3.5 has reached its EOL in September 2020: https://www.python.org/dev/peps/pep-0478/

OpenTelemetry for Python dropped support for Python 3.5 in open-telemetry/opentelemetry-python@d21793d.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs in next 7 days. Thank you for your contributions.

[michael-k]

Python 3.6 has reached its EOL in December 2021: https://peps.python.org/pep-0494/

OpenTelemetry for Python is preparing to drop dropped support for Python 3.6, see open-telemetry/opentelemetry-python#2763.

[michael-k]

@jj22ee has dropped support for Python < 3.7 in 2.12, see eg. eaffcc8. But there's still work to do:

• The classifiers still suggest support for Python 2.7 and 3.4–3.6.
• install_requires includes dependencies for Python 2.7
• There's no python_requires to prevent pip from installing 2.12 on Python < 3.7.
• … (only had a rough look so far)