fix python 3.7 tests on macos #18

Job	Run time
test (3.7, ubuntu-latest)	13s
test (3.7, macos-13)	36s
test (3.7, windows-latest)	1m 5s
test (3.8, ubuntu-latest)	14s
test (3.8, macos-13)	20s
test (3.8, windows-latest)	57s
test (3.9, ubuntu-latest)	15s
test (3.9, macos-13)	17s
test (3.9, windows-latest)	53s
test (3.10, ubuntu-latest)	16s
test (3.10, macos-13)	23s
test (3.10, windows-latest)	48s
test (3.11, ubuntu-latest)	16s
test (3.11, macos-13)	23s
test (3.11, windows-latest)	50s
test (3.12, ubuntu-latest)	14s
test (3.12, macos-13)	19s
test (3.12, windows-latest)	56s
test (pypy3.7, ubuntu-latest)	38s
test (pypy3.7, macos-13)	42s
test (pypy3.7, windows-latest)	1m 30s
test (pypy3.8, ubuntu-latest)	34s
test (pypy3.8, macos-13)	38s
test (pypy3.8, windows-latest)	1m 31s
test (pypy3.9, ubuntu-latest)	37s
test (pypy3.9, macos-13)	35s
test (pypy3.9, windows-latest)	1m 19s
test (pypy3.10, ubuntu-latest)	41s
test (pypy3.10, macos-13)	39s
test (pypy3.10, windows-latest)	2m 0s
Indicate completion to Coveralls	5s
	20m 44s

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