Update nightly toolchain for GitHub Actions CI

[Robbepop]

Just a recurring update. No issues with the current nightly toolchain.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.81%. Comparing base (8aefda8) to head (86a5fa7).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/wasmi/src/error.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1571      +/-   ##
==========================================
+ Coverage   72.34%   72.81%   +0.47%     
==========================================
  Files         179      179              
  Lines       16330    16392      +62     
==========================================
+ Hits        11814    11936     +122     
+ Misses       4516     4456      -60     

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