Remove PyPy 2.7 #987

Job	Run time
Run tests on legacy versions (3.7)	1m 30s
Run linters (flake8)	1m 4s
Run tests with coverage	2m 1s
Run tests on legacy versions (pypy3.9)	1m 13s
Run linters (pydocstyle)	1m 4s
Run linters (mypy)	1m 10s
Run tests (3.8)	1m 20s
Run linters (pylint)	1m 9s
Run tests (3.9)	1m 30s
Run tests (3.10)	1m 25s
Run tests (3.11)	1m 23s
Run tests (3.12)	1m 37s
	16m 26s

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