Unbreak Windows CI builds^2

[d-e-s-o]

Force usage of 12.12.4. Evidently, with a constraint of <12.13.0 we end up picking 11 in addition to the most recent 12.13.x o_O

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.50%. Comparing base (5d8814c) to head (29d2ec6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #960   +/-   ##
=======================================
  Coverage   94.50%   94.50%           
=======================================
  Files          57       57           
  Lines       10603    10603           
=======================================
  Hits        10020    10020           
  Misses        583      583           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[d-e-s-o]

I looked into why it was broken to begin with. Seems to be caused by getsentry/symbolic#885, if I am not mistaken, which likely uses newer C++ features not yet support by the LLVM present on windows-latest (or something along those lines). And then dump_syms uses the default features of symbolic-demangle, which pulls in Switft stuff (which of course we couldn't care less about, conceptually). I don't really see a way around this, so we are probably stuck with this arrangement until the windows-latest image includes a higher LLVM or so...