Add test target to Makefile #13

Job	Run time
lint	34s
unit-test (3.10, ubuntu-latest)	21s
build-package	34s
unit-test (3.10, macos-latest)	36s
unit-test (3.10, windows-latest)	1m 2s
unit-test (3.11, macos-latest)	20s
unit-test (3.11, ubuntu-latest)	26s
unit-test (3.11, windows-latest)	1m 4s
unit-test (3.12, macos-latest)	24s
unit-test (3.12, ubuntu-latest)	25s
unit-test (3.12, windows-latest)	1m 1s
unit-test (3.7, ubuntu-latest)	23s
unit-test (3.7, windows-latest)	1m 3s
unit-test (3.8, macos-latest)	48s
unit-test (3.8, ubuntu-latest)	30s
unit-test (3.8, windows-latest)	1m 10s
unit-test (3.9, macos-latest)	38s
unit-test (3.9, ubuntu-latest)	25s
unit-test (3.9, windows-latest)	1m 2s
unit-test (pypy-3.10, ubuntu-latest)	51s
unit-test (pypy-3.10, macos-latest)	53s
unit-test (pypy-3.10, windows-latest)	1m 44s
sign-package	20s
publish-package	22s
	16m 56s

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