Fix issue with moved files not being found when running git diff

[chris-mitchell]

See #60 for more detail

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #61 (9df4273) into main (6180e39) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main      #61   +/-   ##
=========================================
  Coverage     49.08%   49.08%           
  Complexity       47       47           
=========================================
  Files            12       12           
  Lines           436      436           
  Branches         97       97           
=========================================
  Hits            214      214           
  Misses          192      192           
  Partials         30       30           

Impacted Files	Coverage Δ
...in/com/dropbox/affectedmoduledetector/GitClient.kt	10.29% <ø> (ø)

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