More reliable Base32 dependency version

[mattrubin]

Update the Cartfile to depend on a tagged version of Base32, rather than a specific commit hash.

[codecov]

Codecov Report

Merging #160 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #160   +/-   ##
========================================
  Coverage    95.36%   95.36%           
========================================
  Files            6        6           
  Lines          475      475           
  Branches        33       33           
========================================
  Hits           453      453           
  Misses          22       22

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