Disallow literal `0` step in slice expressions #13780

Job	Run time
Test mypyc suite with 32-bit Python	7m 4s
Test suite with py38-ubuntu, mypyc-compiled	17m 58s
Test suite with py38-windows-64	20m 35s
Test suite with py39-ubuntu	16m 33s
Test suite with py310-ubuntu	15m 42s
Test suite with py311-ubuntu, mypyc-compiled	15m 36s
Test suite with py312-ubuntu, mypyc-compiled	17m 34s
Test suite with py313-ubuntu, mypyc-compiled	17m 59s
mypyc runtime tests with py39-macos	6m 2s
Type check our own code (py38-ubuntu)	2m 1s
Type check our own code (py38-windows-64)	2m 42s
Formatting and code style with Black + ruff	31s
	2h 20m 17s

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