fix macos CI

[antond-weta]

Description

The macos CI runners have been updated to Eigen 5.0.1, which is incompatible with Ceres 2.2.0_3.
Calling brew update prior to installing Ceres bumps its version to 2.2.0_4, which fixes the build.

Tests

Checklist:

• I have read the contribution guidelines.
• I have updated the documentation, if applicable. (Check if there is no
  need to update the documentation, for example if this is a bug fix that
  doesn't change the API.)
• I have ensured that the change is tested somewhere in the testsuite
  (adding new test cases if necessary).
• My code follows the prevailing code style of this project. If I haven't
  already run clang-format before submitting, I definitely will look at the CI
  test that runs clang-format and fix anything that it highlights as being
  nonconforming.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.81%. Comparing base (1b86a2f) to head (dbd46e1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #217      +/-   ##
==========================================
+ Coverage   72.56%   79.81%   +7.25%     
==========================================
  Files          10       11       +1     
  Lines        2114     2150      +36     
  Branches      317      325       +8     
==========================================
+ Hits         1534     1716     +182     
+ Misses        580      434     -146     

see 3 files with indirect coverage changes

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