Set MSRV to 1.70 #924

Job	Run time
Cross build from macOS to Linux (x86_64-unknown-linux-gnu)	1m 47s
rustfmt	3s
Cross build from macOS to Linux (FIPS) (x86_64-unknown-linux-gnu)	4m 53s
clippy	8m 4s
Test features	7m 10s
Test (stable)	2m 0s
Test FIPS integration	2m 45s
Test (arm-android)	1m 57s
Test (arm64-android)	2m 3s
Test (i686-android)	1m 53s
Test (x86_64-android)	1m 46s
Test (aarch64-ios)	2m 10s
Test (aarch64-ios-sim)	2m 13s
Test (x86_64-ios)	2m 16s
Test (i686-linux)	2m 11s
Test (arm-linux)	2m 9s
Test (aarch64-linux)	2m 21s
Test (arm64-macos)	2m 6s
Test (x86_64-macos)	2m 18s
Test (x86_64-mingw)	6m 58s
Test (i686-msvc)	5m 58s
Test (x86_64-msvc)	6m 2s
	1h 11m 3s

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