Fix CI, Bump MSRV to 1.70.0 #329

Job	Run time
rust_clippy_check_ubuntu	5m 47s
rustfmt_check (macos-latest)	24s
build_dynamic_and_test_windows_pre	7m 19s
rustfmt_check (windows-latest)	42s
build_static_and_test_ubuntu (release/4.3, nightly, no valgrind)	5m 52s
docs_rs_check	58s
rust_clippy_check_windows	26m 55s
build_static_and_test_ubuntu (release/4.3, 1.64.0, no valgrind)	5m 49s
rustfmt_check (ubuntu-latest)	15s
build_static_and_test_ubuntu (release/5.0, nightly, no valgrind)	5m 54s
build_static_and_test_ubuntu (release/5.0, 1.64.0, no valgrind)	6m 28s
build_static_and_test_ubuntu (release/6.0, nightly, valgrind)	4m 57s
build_static_and_test_ubuntu (release/6.0, nightly, no valgrind)	6m 56s
build_static_and_test_ubuntu (release/6.0, 1.64.0, no valgrind)	6m 36s
build_dynamic_and_test_windows (nightly)	2m 13s
build_dynamic_and_test_windows (1.64.0)	2m 42s
	1h 29m 47s

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