move build env to a separate directory #88

Job	Run time
test_ubuntu (3.7)	41s
test_ubuntu (3.8)	40s
test_macos (3.7)	1m 24s
test_windows (3.7)	3m 21s
test_ubuntu (3.9)	6h 0m 14s
test_macos (3.8)	1m 25s
test_windows (3.8)	3m 12s
test_ubuntu (3.10)	40s
test_macos (3.9)	4m 2s
test_windows (3.9)	3m 26s
test_ubuntu (3.11)	45s
test_macos (3.10)	4m 2s
test_windows (3.10)	3m 21s
test_ubuntu (3.12)	46s
test_windows (3.11)	3m 19s
test_macos (3.11)	1m 50s
test_macos (3.12)	1m 49s
test_windows (3.12)	3m 21s
Build windows PYPI package	0s
Conda Build (Python ${{ matrix.python-version }} ${{ matrix.os }})	0s
Build macos PYPI package (3.7)	1m 33s
Conda Build (Python 3.7)	6h 0m 17s
Build macos PYPI package (3.8)	1m 48s
Build macos PYPI package (3.9)	1m 39s
Conda Build (Python 3.8)	2m 1s
Build macos PYPI package (3.10)	1m 54s
Conda Build (Python 3.9)	1m 53s
Build macos PYPI package (3.11)	2m 25s
Conda Build (Python 3.10)	2m 0s
Build macos PYPI package (3.12)	2m 58s
Conda Build (Python 3.11)	2m 11s
Conda Build (Python 3.12)	18m 54s
Conda Build (Python ${{ matrix.python-version }})	0s
Build manylinux PYPI package	0s
	13h 17m 51s

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