Remove `python-gil` requirement and enable free-threaded Python #6168

Job	Run time
build_linux (3.13)	5m 45s
build_linux (3.10)	5m 26s
build_linux (3.11)	5m 43s
build_windows (3.12)	2m 42s
build_linux (3.14)	5m 43s
build_linux (3.12)	5m 51s
build_windows (3.10)	2m 49s
build_windows (3.14, 3.14.* *_cp314)	2m 54s
build_windows (3.14)	2m 51s
build_linux (3.14, 3.14.* *_cp314)	5m 45s
build_windows (3.11)	2m 51s
build_windows (3.13)	2m 52s
test_windows	0s
upload_windows	0s
test_examples_linux (3.11, false, ubuntu-22.04)	9m 7s
test_linux (3.14, false, ubuntu-22.04)	2m 38s
test_linux (3.11, false, ubuntu-22.04)	2m 59s
test_linux (3.14, 3.14.* *_cp314, false, ubuntu-22.04)	2m 58s
test_linux (3.13, false, ubuntu-22.04)	4m 47s
test_linux (3.10, false, ubuntu-22.04)	2m 49s
test_linux (3.12, false, ubuntu-22.04)	3m 21s
upload_linux	0s
Clean up anaconda packages	0s
	1h 19m 51s

Provide feedback