Tests

Make ccache-action respect environment variables #308

Job	Run time
test_docker_alpine	15s
test_docker_ubuntu	10s
build	14s
test_ccache (ubuntu-latest, bash, sccache)	4s
test_option_append_timestamp (true)	32s
test_ccache (ubuntu-latest, bash, ccache)	7s
test_option_create_symlink (true)	9s
test_option_append_timestamp (false)	9s
test_option_save (true)	10s
test_ccache (macos-latest, bash, sccache)	16s
test_option_save (false)	9s
test_option_create_symlink (false)	11s
test_ccache (macos-latest, bash, ccache)	17s
test_ccache (windows-latest, bash, sccache)	14s
test_ccache (windows-latest, bash, ccache)	21s
test_ccache (windows-latest, powershell, sccache)	15s
test_ccache (windows-latest, powershell, ccache, true)	15s
test_cache_miss	0s
test_restore_keys	0s
test_cache_hit	0s
	3m 48s

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