Fix some typos

[striezel]

Fix some typos, no functional changes intended.

[prestwich]

changes verified to be non-functional

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.09 🎉

Comparison is base (b58a33f) 84.40% compared to head (c236cf4) 84.49%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #235      +/-   ##
==========================================
+ Coverage   84.40%   84.49%   +0.09%     
==========================================
  Files          49       49              
  Lines        5872     5870       -2     
==========================================
+ Hits         4956     4960       +4     
+ Misses        916      910       -6     

Impacted Files	Coverage Δ
src/algorithms/gcd/matrix.rs	94.65% <ø> (ø)
src/modular.rs	99.59% <100.00%> (ø)

... and 3 files with indirect coverage changes

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