Coverage: Implement fail_under #2309

Job	Run time
Run tests (3.10.4)	14s
Run tests (3.9)	11s
Run tests (3.12.0)	20s
Run tests (3.12)	15s
Run tests (3.11)	10s
Run tests (3.14)	19s
Run tests (3.11.0)	17s
Run tests (3.10)	12s
Run tests (3.13)	13s
Run tests (3.9.12)	16s
Run tests (pypy3.9)	14s
Run tests (3.13.0)	15s
Run tests (pypy3.10)	11s
Run tests (pypy3.11)	10s
Report coverage	14s
Create an issue if daily tests failed	0s
	3m 31s

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