Remove dependency on repoze.lru Python package

[Mandrenkov]

Context:
There is a Python installation dependency on repoze.lru which uses a license that may be unsuitable for some projects.

Description of the Change:

• Removed repoze.lru as a Python dependency; functools.lru_cache() is now used in place of repoze.lru_cache().

Benefits:

• The Walrus has fewer dependencies.

Possible Drawbacks:
None.

Related GitHub Issues:
None.

[nquesada]

Thanks @Mandrenkov ! This is a most welcome change.

[codecov]

Codecov Report

Merging #293 (d1b298a) into master (be0339e) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #293   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           21        21           
  Lines         1446      1446           
=========================================
  Hits          1446      1446           

Impacted Files	Coverage Δ
thewalrus/_low_rank_haf.py	100.00% <100.00%> (ø)

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[thisac]

Thanks @Mandrenkov! 💯