chore: Bump MSRV to 1.82

[larseggert]

And address some TODOs that were enabled by the new MSRV.

[codecov]

Codecov Report

Attention: Patch coverage is 96.15385% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.90%. Comparing base (7a76763) to head (352a7fa).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/bsd.rs	97.56%	0 Missing and 1 partial ⚠️
src/lib.rs	50.00%	1 Missing ⚠️
src/linux.rs	97.14%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #91      +/-   ##
==========================================
+ Coverage   86.53%   86.90%   +0.36%     
==========================================
  Files           5        5              
  Lines         557      565       +8     
  Branches      557      565       +8     
==========================================
+ Hits          482      491       +9     
+ Misses         49       48       -1     
  Partials       26       26              

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[larseggert]

OpenBSD's Rust package is 1.81. NetBSD and FreeBSD hit rust-lang/rust#137640.