Bump supported cpython version to 3.14 for testing #12392

Job	Run time
fmt	15s
resolve	6s
check-msrv	1m 17s
semver-checks	28s
python${{ matrix.python-version }}-${{ matrix.platform.python-architecture }} ${{ matrix.platform.os }} rust-${{ matrix.rust }}	0s
careful	0s
coverage windows-latest	6m 33s
clippy/aarch64-apple-darwin/stable	1m 26s
coverage macos-latest	6m 47s
docsrs	0s
Free threaded tests - ubuntu-latest	6m 48s
clippy/x86_64-unknown-linux-gnu/stable	1m 22s
coverage ubuntu-latest	6m 47s
Free threaded tests - macos-latest	6m 48s
Free threaded tests - windows-latest	6m 33s
valgrind	0s
clippy/powerpc64le-unknown-linux-gnu/stable	1m 8s
clippy/s390x-unknown-linux-gnu/stable	1m 22s
check-feature-powerset ${{ matrix.rust }}	0s
emscripten	0s
clippy/wasm32-wasip1/stable	1m 22s
clippy/x86_64-pc-windows-msvc/stable	1m 7s
clippy/i686-pc-windows-msvc/stable	1m 9s
test-debug	0s
test-version-limits	0s
clippy/x86_64-unknown-linux-gnu/beta	1m 24s
test-cross-compilation ${{ matrix.os }} -> ${{ matrix.target }}	0s
test-cross-compilation-windows	0s
python3.12-x64 ubuntu-latest rust-nightly / build	29s
python3.12-x64 macos-13 rust-stable / build	1s
python3.12-arm64 macos-latest rust-stable / build	29s
python3.12-x64 ubuntu-latest rust-stable / build	29s
python3.12-x86 windows-latest rust-stable / build	7s
python3.12-x64 windows-latest rust-stable / build	8s
conclusion	1s
	54m 26s

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