Deprecate `squeeze` in GroupBy. #10912

Job	Run time
detect ci trigger	5s
Doctests	1m 43s
Minimum Version Policy (bare-minimum)	35s
Mypy	1m 39s
Minimum Version Policy (min-all-deps)	43s
Mypy 3.9	1m 51s
Pyright	0s
Pyright 3.9	0s
	6m 36s

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