ci: Remove apk add git #2793

Job	Run time
test (no rustup)	1m 54s
test (1.26)	7m 54s
test (stable)	5m 53s
test (1.30)	6m 19s
test (beta)	5m 40s
test (1.31)	6m 37s
test (nightly)	5m 54s
test (1.36)	7m 21s
test (nightly, macos-11)	11m 41s
test (1.39)	7m 23s
test (1.41)	7m 39s
test (nightly, windows-2019)	10m 9s
deny / deny	12s
miri / miri	52s
msrv / msrv	2m 16s
release-dry-run / prepare	8s
tidy / tidy	1m 11s
release-dry-run / build (aarch64-unknown-linux-gnu)	1m 19s
release-dry-run / build (aarch64-unknown-linux-musl)	1m 0s
release-dry-run / build (aarch64-apple-darwin, macos-11)	1m 53s
release-dry-run / build (aarch64-pc-windows-msvc, windows-2019)	3m 44s
release-dry-run / build (x86_64-unknown-linux-gnu)	49s
release-dry-run / build (x86_64-unknown-linux-musl)	45s
release-dry-run / build (x86_64-apple-darwin, macos-11)	1m 43s
release-dry-run / build (x86_64-pc-windows-msvc, windows-2019)	1m 44s
release-dry-run / build (x86_64-unknown-freebsd)	1m 25s
release-dry-run / build (universal-apple-darwin, macos-11)	2m 15s
	1h 45m 40s

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