fix: avoid confusing gray color for Add to calendar in the agenda

[evyncke]

Fixing #7096 by using the Bootstrap 'info' rather than 'secondary' color for Add to calendar.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.94%. Comparing base (187c2c5) to head (013a75a).
Report is 73 commits behind head on main.

❗ Current head 013a75a differs from pull request most recent head ccc11db. Consider uploading reports for the commit ccc11db to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7210      +/-   ##
==========================================
- Coverage   88.98%   88.94%   -0.05%     
==========================================
  Files         291      291              
  Lines       40717    41067     +350     
==========================================
+ Hits        36233    36525     +292     
- Misses       4484     4542      +58     

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[evyncke]

I am lost now about what I did wrong wrt whitespaces (sorry Nick).

Anyway, it is very simple to redo the change: change #6C757D into #54B4D3 in two locations in the file.

[NGPixel]

I've reset your PR to the latest main commit (to fix the whitespace issues) and made similar color changes to the buttons.

I also fixed the timezone buttons text color in dark mode being hard to read.

[evyncke]

Thanks Nick