Harden our CI workflows and add a zizmor workflow

[poljar]

No description provided.

[github-advanced-security]

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[codspeed-hq]

Merging this PR will not alter performance

✅ 50 untouched benchmarks

---

_{Comparing poljar/zizmor (892474a) with main (1e74c48)}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.89%. Comparing base (1e74c48) to head (892474a).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6460   +/-   ##
=======================================
  Coverage   89.89%   89.89%           
=======================================
  Files         379      379           
  Lines      104699   104699           
  Branches   104699   104699           
=======================================
+ Hits        94114    94120    +6     
  Misses       6983     6983           
+ Partials     3602     3596    -6     

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[poljar]

The rust-toolchain action warning is a bit misleading. More details here: zizmorcore/zizmor#1817.

As such I'll dismiss the warning.