Tests

Bump nix to 0.29 #1707

Job	Run time
quick-test	2m 54s
pr-mutants (cargo)	24s
tests-from-tarball (ubuntu-latest)	2m 21s
pr-mutants (nextest)	24s
cargo-mutants (0, cargo)	12m 53s
test (macOS-latest, stable)	5m 17s
cargo-mutants (1, cargo)	7m 55s
test (macOS-latest, nightly)	9m 30s
cargo-mutants (2, cargo)	16m 6s
test (macOS-latest, 1.78)	5m 36s
cargo-mutants (3, cargo)	12m 20s
test (ubuntu-latest, stable)	4m 59s
cargo-mutants (4, cargo)	8m 5s
test (ubuntu-latest, nightly)	8m 40s
cargo-mutants (5, cargo)	9m 28s
test (ubuntu-latest, 1.78)	4m 52s
cargo-mutants (6, cargo)	11m 9s
test (windows-latest, stable)	7m 23s
cargo-mutants (7, cargo)	7m 47s
test (windows-latest, nightly)	16m 19s
cargo-mutants (8, cargo)	8m 8s
cargo-mutants (9, cargo)	13m 0s
test (windows-latest, 1.78)	7m 13s
overall-result	1s
	3h 2m 44s

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