Allow environment variables to contain numbers #4200

Job	Run time
cargo-deny	25s
check	19s
clippy (macos-latest)	29s
clippy (ubuntu-latest)	26s
fmt	11s
clippy (windows-latest)	57s
generate-matrix	19s
shellcheck	16s
test (macos-latest)	54s
test (ubuntu-latest)	57s
test (windows-latest)	2m 58s
foreign	2m 49s
remote	1m 59s
bisect	4m 5s
target (${{ matrix.pretty }},${{ matrix.os }})	0s
docker-in-docker	3m 47s
podman	1m 58s
publish	0s
conclusion	1s
Coverage	6s
	22m 56s

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