[ENH] move tests for dependency checks and deep_equals to utils module

[fkiraly]

This PR moves the tests for dependency checks and deep_equals to the utils module where those utilities reside.

[codecov-commenter]

Codecov Report

Merging #217 (deb52fa) into main (d840e75) will not change coverage.
The diff coverage is 100.00%.

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@@           Coverage Diff           @@
##             main     #217   +/-   ##
=======================================
  Coverage   83.59%   83.59%           
=======================================
  Files          43       43           
  Lines        2841     2841           
=======================================
  Hits         2375     2375           
  Misses        466      466           

Files Changed	Coverage Δ
skbase/testing/test_all_objects.py	79.43% <100.00%> (ø)
skbase/utils/dependencies/tests/__init__.py	100.00% <100.00%> (ø)
...tils/dependencies/tests/test_check_dependencies.py	100.00% <100.00%> (ø)
skbase/utils/tests/test_deep_equals.py	100.00% <100.00%> (ø)