Replace pytest-freezegun with pytest-freezer

[dariuszd21]

What needs to get done

Change the dependency and fix all the problems, that appear from the difference between those two packages.

Why it needs to get done

pytest-freezegun is unmaintained since 2020 and reports deprecation warnings during tests
See:
ktosiek/pytest-freezegun#19
and
https://github.com/pytest-dev/pytest-freezer

[syncronize-issues-to-jira]

Thank you for reporting us your feedback!

The internal ticket has been created: https://warthogs.atlassian.net/browse/CRAFT-3574.

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[lengau]

We should probably do this across all our repos (IIRC craft-providers heavily uses this.)