ci: run beta clippy as an allowed-to-fail job #7380

Job	Run time
fmt	20s
emscripten	0s
test-debug	8m 52s
semver-checks	35s
python${{ matrix.python-version }}-${{ matrix.platform.python-architecture }} ${{ matrix.platform.os }} rust-${{ matrix.rust }}	0s
careful	0s
clippy/x86_64-apple-darwin/stable	11m 50s
check-msrv	10m 57s
clippy/x86_64-unknown-linux-gnu/stable	8m 54s
coverage-windows	4s
valgrind	0s
clippy/powerpc64le-unknown-linux-gnu/stable	8m 1s
coverage-macos	7s
clippy/s390x-unknown-linux-gnu/stable	7m 42s
coverage-ubuntu	14m 28s
clippy/wasm32-wasi/stable	7m 37s
clippy/x86_64-pc-windows-msvc/stable	12m 16s
clippy/i686-pc-windows-msvc/stable	11m 12s
clippy/x86_64-unknown-linux-gnu/beta	8m 3s
python3.12-x64 windows-latest rust-stable / build	13m 3s
python3.12-x64 ubuntu-latest rust-stable / build	8m 19s
python3.12-x86 windows-latest rust-stable / build	9m 56s
python3.12-x64 macos-latest rust-stable / build	9m 4s
python3.12-x64 ubuntu-latest rust-nightly / build	7m 24s
conclusion	1s
	2h 38m 45s

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