Bump num-traits and num-bigint #1527

Job	Run time
Wheel on macos-latest py-3.7	3m 46s
Wheel on ubuntu-latest py-3.7	3m 38s
Wheel on windows-latest py-3.7	5m 0s
Checks	1m 12s
coverage	12m 32s
Run fuzz targets (macos-latest, 3.7)	41m 56s
Run fuzz targets (ubuntu-latest, 3.7)	27m 56s
Unit tests (macos-latest, 3.7)	9m 21s
Unit tests (ubuntu-latest, 3.7)	5m 46s
Unit tests (windows-latest, 3.7)	12m 23s
	2h 3m 30s

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