Use SPDX license expression #1009

Job	Run time
mypy	21s
build (3.6, yes, ubuntu-20.04)	2m 45s
build (3.6, no, ubuntu-20.04)	2m 37s
build_python_27 (ubuntu-20.04, yes)	2m 45s
python_no_gil	3m 9s
build_python_27 (ubuntu-20.04, no)	2m 42s
build (3.7, yes, ubuntu-20.04)	2m 31s
build_python_27 (windows-latest, yes)	4m 12s
test_c_linux (0, x64)	55s
build_python_27 (windows-latest, no)	4m 13s
build (3.7, no, ubuntu-20.04)	2m 33s
test_c_linux (0, x32)	1m 4s
build (3.8, yes, ubuntu-20.04)	2m 35s
test_c_linux (1, x64)	56s
build (3.8, no, ubuntu-20.04)	2m 26s
test_c_linux (1, x32)	1m 31s
test_c_windows (x64)	1m 4s
build (3.9, yes, ubuntu-20.04)	2m 26s
test_c_windows (win32)	38s
build (3.9, no, ubuntu-20.04)	2m 28s
build (3.10, yes, ubuntu-20.04)	2m 21s
build (3.10, no, ubuntu-20.04)	2m 28s
build (3.11, yes, ubuntu-20.04)	2m 4s
build (3.11, no, ubuntu-20.04)	2m 2s
build (3.12, yes, ubuntu-20.04)	2m 4s
build (3.12, no, ubuntu-20.04)	2m 11s
build (3.13-dev, yes, ubuntu-20.04)	2m 12s
build (3.13-dev, no, ubuntu-20.04)	2m 26s
build (3.12, yes, macos-12)	3m 23s
build (3.12, no, windows-latest)	3m 52s
build (3.12, yes, windows-latest)	4m 6s
build (pypy2.7, no, ubuntu-latest)	1m 34s
build (pypy3.9, no, ubuntu-latest)	1m 47s
	1h 16m 21s

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