Use SPDX license expression #1008

Job	Run time
mypy	17s
build_python_27 (ubuntu-20.04, yes)	26s
build_python_27 (ubuntu-20.04, no)	24s
build (3.6, yes, ubuntu-20.04)	15s
python_no_gil	29s
build_python_27 (windows-latest, yes)	23s
build (3.6, no, ubuntu-20.04)	15s
build_python_27 (windows-latest, no)	22s
build (3.7, yes, ubuntu-20.04)	17s
build (3.7, no, ubuntu-20.04)	13s
test_c_linux (0, x64)	53s
build (3.8, yes, ubuntu-20.04)	13s
test_c_windows (x64)	49s
build (3.8, no, ubuntu-20.04)	14s
test_c_windows (win32)	1m 8s
build (3.9, yes, ubuntu-20.04)	1s
test_c_linux (0, x32)	1m 1s
build (3.9, no, ubuntu-20.04)	11s
test_c_linux (1, x64)	50s
build (3.10, yes, ubuntu-20.04)	12s
test_c_linux (1, x32)	1m 8s
build (3.10, no, ubuntu-20.04)	16s
build (3.11, yes, ubuntu-20.04)	14s
build (3.11, no, ubuntu-20.04)	11s
build (3.12, yes, ubuntu-20.04)	14s
build (3.12, no, ubuntu-20.04)	11s
build (3.13-dev, yes, ubuntu-20.04)	13s
build (3.13-dev, no, ubuntu-20.04)	18s
build (3.12, yes, macos-12)	18s
build (3.12, no, windows-latest)	11s
build (3.12, yes, windows-latest)	11s
build (pypy2.7, no, ubuntu-latest)	1s
build (pypy3.9, no, ubuntu-latest)	1s
	12m 20s

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