Tests

Bump MSRV to 1.78 (#464) #1706

Job	Run time
quick-test	2m 43s
tests-from-tarball (ubuntu-latest)	2m 29s
cargo-mutants (0, cargo)	13m 21s
test (macOS-latest, stable)	8m 2s
pr-mutants	0s
cargo-mutants (1, cargo)	7m 51s
test (macOS-latest, nightly)	10m 34s
cargo-mutants (2, cargo)	16m 4s
test (macOS-latest, 1.78)	7m 39s
cargo-mutants (3, cargo)	12m 26s
test (ubuntu-latest, stable)	7m 10s
cargo-mutants (4, cargo)	8m 12s
test (ubuntu-latest, nightly)	8m 37s
cargo-mutants (5, cargo)	9m 26s
test (ubuntu-latest, 1.78)	7m 7s
cargo-mutants (6, cargo)	10m 33s
test (windows-latest, stable)	12m 15s
cargo-mutants (7, cargo)	7m 54s
test (windows-latest, nightly)	16m 5s
cargo-mutants (8, cargo)	8m 34s
cargo-mutants (9, cargo)	12m 57s
test (windows-latest, 1.78)	11m 29s
overall-result	1s
	3h 21m 29s

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