Restore mixpanel token for Homebrew build

[jribbink]

Closes #1946

Description

Restores the Mixpanel token which was unintentionally removed in a prior commit.

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For contributor use:

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.26%. Comparing base (f52455f) to head (d4778c8).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1948   +/-   ##
=======================================
  Coverage   28.26%   28.26%           
=======================================
  Files          96       96           
  Lines        6648     6648           
=======================================
  Hits         1879     1879           
  Misses       4585     4585           
  Partials      184      184           

Flag	Coverage Δ
unittests	28.26% <ø> (ø)

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