Update MSRV to 1.81 #15636

Job	Run time
paths-filter	4s
Checks / Check if running codegen would produce any changes	1m 8s
Checks / Rerun lints	34s
Checks / Lint markdown	16s
Checks / Spell Check	8s
Checks / markdown-paths-filter	7s
Checks / Misc formatting	15s
C++ tests	0s
Minimum CLI Build / Set Config (linux-x64)	1s
Build web viewer / Build web viewer	3m 15s
Build rerun_js / Build rerun_js	3m 7s
Python Checks / Python lints (ruff, mypy, …)	42s
Python Checks / Test Python Docs	29s
Rust Checks / Rust lints (fmt, check, clippy, tests, doc)	10m 8s
Rust Checks / Test on ${{ matrix.name }}	0s
Deploy Landing Preview / Deploy	54s
Checks / Check links	17s
Minimum CLI Build / Build rerun-cli (ubuntu-latest-16-cores)	5m 28s
Upload Web / Upload web build to google cloud (wasm32 + wasm-bindgen)	13s
Minimum Wheel Build / Set Config (linux-x64)	1s
Minimum Wheel Build / Build Wheels (ubuntu-latest-16-cores)	2m 26s
Minimum Wheel Test / Set Config (linux-x64)	1s
Minimum Wheel Test / Test Wheels (ubuntu-latest-16-cores)	3m 45s
	33m 19s

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