chore: dont lock poetry

[Jan Kowalleck]

this is a library, expected to be usable in various environments.
therefore, it is needed to run the lib in various test envs, too.

the poetry lock file is making this hard.
therefore: lets remove the poetry lock file, if possible.

for QA reasons, the ci/tests should run periodically, to check if all dependencies still match
the dev-dependnecies should be pinned to exact versions, to make testing reliable, despite the absence if a lock file.

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and for some reasons, the current lock file appears to cause problems on CI: