Specify 1.67.1 as MSRV #176

Job	Run time
build (windows-2019, stable)	1m 42s
build (windows-2019, 1.67)	3m 35s
build (ubuntu-latest, stable)	17s
aarch64-apple-ios (stable)	48s
cross-linux (stable, aarch64, aarch64-unknown-linux-gnu, aarch64-linux-gnu)	45s
aarch64-apple-ios (1.67)	5m 13s
android (stable, aarch64-linux-android)	14s
cross-linux (stable, arm, armv7-unknown-linux-gnueabihf, arm-linux-gnueabihf)	40s
android (stable, armv7-linux-androideabi)	19s
cross-linux (stable, i386, i686-unknown-linux-gnu, i686-linux-gnu)	45s
build (ubuntu-latest, 1.67)	2m 26s
android (stable, x86_64-linux-android)	24s
cross-linux (1.67, aarch64, aarch64-unknown-linux-gnu, aarch64-linux-gnu)	2m 51s
cross-windows (stable, aarch64-pc-windows-msvc)	2m 8s
build (macos-latest, stable)	41s
android (stable, i686-linux-android)	14s
cross-linux (1.67, arm, armv7-unknown-linux-gnueabihf, arm-linux-gnueabihf)	3m 11s
cross-windows (stable, i686-pc-windows-msvc)	2m 12s
build (macos-latest, 1.67)	3m 45s
android (1.67, aarch64-linux-android)	2m 24s
cross-linux (1.67, i386, i686-unknown-linux-gnu, i686-linux-gnu)	2m 52s
cross-windows (1.67, aarch64-pc-windows-msvc)	3m 41s
android (1.67, armv7-linux-androideabi)	2m 21s
cross-windows (1.67, i686-pc-windows-msvc)	3m 39s
android (1.67, x86_64-linux-android)	2m 24s
freebsd (14.0, stable)	3m 10s
android (1.67, i686-linux-android)	2m 49s
freebsd (14.0, 1.67)	6m 2s
freebsd (13.2, stable)	3m 30s
freebsd (13.2, 1.67)	5m 48s
	1h 10m 50s

Provide feedback