depr: deprecate utils.strings

[dkrako]

⚠️ Deprecation

utils.strings is deprecated and will be removed in pymovements v0.26.0

Description

Deprecate utils.strings as none of the included are intended for the end-user.

The following warning is printed:

DeprecationWarning: Call to deprecated function (or staticmethod) curly_to_regex. (This module will be removed in v0.26.0.) -- Deprecated since version v0.21.0.

partly resolves #999

Implemented changes

• moved utils/strings.py to _utils/_strings.py and adjusted to new location
• use _utils.strings in remaining source
• created deprecated function in utils/strings.py
• moved tests/unit/utils/strings_test.py to tests/unit/_utils/_strings_test.py
• add test that functions are correctly deprecated
• add test that functions are removed in planned version

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (87487d0) to head (bc23f86).

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1031   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           79        80    +1     
  Lines         3588      3595    +7     
  Branches       645       645           
=========================================
+ Hits          3588      3595    +7     

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[SiQube]

thank you for your PR, just some minor questions/feedback