Deprecate `squeeze` in GroupBy. #10909

Job	Run time
detect ci trigger	3s
Mypy 3.9	19s
Doctests	19s
Mypy	19s
Minimum Version Policy (bare-minimum)	32s
Minimum Version Policy (min-all-deps)	20s
Pyright	0s
Pyright 3.9	0s
	1m 52s

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