fix: stamina tests

[Joltras]

Proposed changes

The stamina package contains different kinds of tests, but some of them were disabled due to an issue with the testing framework in the past. Now that it is possible to set a custom player provider during tests, this pull request re-enables them.

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

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• I have read the CONTRIBUTING.md
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)