MNT: bump required rich version to 10.13, adapt tests accordingly (no actual change in behaviour)

[neutrinoceros]

No description provided.

[codecov]

Codecov Report

Merging #144 (48b5eba) into main (ea875d8) will decrease coverage by 0.91%.
The diff coverage is 100.00%.

❗ Current head 48b5eba differs from pull request most recent head 2753217. Consider uploading reports for the commit 2753217 to get more accurate results

@@            Coverage Diff             @@
##             main     #144      +/-   ##
==========================================
- Coverage   98.39%   97.47%   -0.92%     
==========================================
  Files          10       10              
  Lines         435      435              
==========================================
- Hits          428      424       -4     
- Misses          7       11       +4     

Flag	Coverage Δ
unittests	97.47% <100.00%> (-0.92%)	⬇️

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Impacted Files	Coverage Δ
tests/test_builtin.py	100.00% <100.00%> (ø)
tests/test_cli.py	96.03% <100.00%> (-3.97%)	⬇️
tests/test_stdlib.py	100.00% <100.00%> (ø)
wxc/__init__.py	100.00% <100.00%> (ø)
wxc/cli.py	93.97% <100.00%> (ø)

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