Bump MSRV to `1.77` #4846

Job	Run time
Build the fuzzers	3m 31s
Run the fuzzers (fuzz_test, true)	4m 5s
Run the fuzzers (fuzz_date, false)	3m 54s
Run the fuzzers (fuzz_expr, true)	3m 57s
Run the fuzzers (fuzz_printf, false)	3m 7s
Run the fuzzers (fuzz_echo, true)	4m 1s
Run the fuzzers (fuzz_seq, false)	2m 56s
Run the fuzzers (fuzz_sort, false)	3m 9s
Run the fuzzers (fuzz_wc, false)	2m 57s
Run the fuzzers (fuzz_cut, false)	3m 2s
Run the fuzzers (fuzz_split, false)	3m 13s
Run the fuzzers (fuzz_tr, false)	3m 11s
Run the fuzzers (fuzz_env, false)	3m 0s
Run the fuzzers (fuzz_parse_glob, true)	3m 52s
Run the fuzzers (fuzz_parse_size, true)	3m 52s
Run the fuzzers (fuzz_parse_time, true)	4m 0s
Run the fuzzers (fuzz_seq_parse_number, true)	3m 54s
	59m 41s

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