What does this implement/fix? Explain your changes.

Skips checking for a linked libpython.so on Unix unless Py_ENABLE_SHARED is set. If it's not set, all symbols are in the base image.

Does this close any currently open issues?

#1388

Any other comments?

...

Checklist

Check all those that are applicable and complete.

• Make sure to include one or more tests for your change
• If an enhancement PR, please create docs and at best an example
• Add yourself to AUTHORS
• Updated the CHANGELOG