Remove `python-gil` requirement and enable free-threaded Python #6344

Job	Run time
build_linux (3.10)	6m 16s
build_linux (3.11)	6m 45s
build_windows (3.12)	8m 33s
build_windows (3.10)	8m 47s
build_linux (3.13)	6m 21s
build_linux (3.14, 3.14.* *_cp314)	6m 15s
build_linux (3.12)	6m 23s
build_windows (3.14)	8m 37s
build_windows (3.13)	8m 45s
build_windows (3.14, 3.14.* *_cp314)	9m 17s
build_windows (3.11)	8m 44s
build_linux (3.14)	6m 23s
test_examples_linux (3.14, 3.14.* *_cp314, false, ubuntu-latest)	5m 15s
test_examples_linux (3.14, false, ubuntu-latest)	5m 20s
test_linux (3.14, false, ubuntu-latest)	3m 38s
test_linux (3.14, 3.14.* *_cp314, false, ubuntu-22.04)	3m 48s
test_linux (3.13, false, ubuntu-latest)	2m 47s
test_linux (3.12, false, ubuntu-latest)	3m 14s
test_linux (3.10, false, ubuntu-latest)	3m 2s
test_linux (3.11, false, ubuntu-latest)	3m 3s
test_windows (3.13, false, windows-latest)	3m 41s
test_windows (3.10, false, windows-latest)	3m 42s
test_windows (3.11, false, windows-latest)	4m 8s
test_windows (3.12, false, windows-latest)	3m 30s
test_windows (3.14, false, windows-latest)	3m 42s
test_windows (3.14, 3.14.* *_cp314, false, windows-latest)	3m 23s
upload_linux	-1s
upload_windows	0s
Clean up anaconda packages	0s
	2h 23m 18s

Provide feedback