[CI] Drop brew update

[SeanNaren]

What does this PR do?

Voodoo I think has fixed the issue...

Fixes #<issue_number>

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[codecov]

Codecov Report

Merging #6985 (c0d9bad) into master (644e7aa) will decrease coverage by 5%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #6985    +/-   ##
=======================================
- Coverage      92%     87%    -5%     
=======================================
  Files         194     194            
  Lines       12368   12368            
=======================================
- Hits        11349   10699   -650     
- Misses       1019    1669   +650