Bump proptest from 1.2.0 to 1.3.1 #3860

Job	Run time
coverage	4m 23s
Check	49s
Lints (beta)	43s
Lints (stable)	33s
test (beta)	2m 32s
test (stable)	2m 19s
test_all_features	16m 6s
test (windows)	5m 9s
test (macos)	3m 11s
Check if wasm-pack builds a valid package for the sourmash crate	2m 0s
Run tests under wasm32-wasi	2m 56s
Check if cbindgen runs cleanly for generating the C headers	1m 42s
minimum_rust_version	4m 56s
Publish (dry-run)	56s
	48m 15s

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