Add `bigdecimal` as a dependency #23

Job	Run time
cross-compile-linux	7s
cross-compile-windows (x64-mingw32)	1m 0s
install-macos-m1 (2.7)	55s
cross-compile-windows (x86-mingw32)	47s
install-windows-native (2.7)	4m 14s
install-macos-m1 (3.0)	20s
install-windows-native (3.0)	1m 51s
cross-compile-windows (x64-mingw-ucrt)	1m 9s
install-macos-m1 (3.1)	19s
install-windows-native (3.1)	1m 53s
install-macos-m1 (3.2)	23s
install-windows-native (3.2)	1m 41s
install-macos-m1 (3.3)	20s
install-windows-native (3.3)	1m 31s
test-linux (2017, 2.7)	1m 22s
test-linux (2017, 3.0)	1m 19s
test-linux (2017, 3.1)	1m 17s
test-linux (2017, 3.2)	1m 12s
test-linux (2017, 3.3)	1m 17s
test-linux (2019, 2.7)	1m 24s
test-linux (2019, 3.0)	1m 11s
test-linux (2019, 3.1)	1m 18s
test-linux (2019, 3.2)	1m 22s
test-linux (2019, 3.3)	1m 16s
test-linux (2022, 2.7)	1m 37s
test-linux (2022, 3.0)	1m 22s
test-linux (2022, 3.1)	1m 18s
test-linux (2022, 3.2)	1m 15s
test-linux (2022, 3.3)	1m 25s
install-windows-ucrt (3.1)	1m 14s
install-windows-mingw (2.7)	3m 14s
test-windows-mingw (2019, 2.7)	8m 31s
install-windows-ucrt (3.2)	1m 25s
test-windows-ucrt (2019, 3.1)	5m 43s
install-windows-mingw (3.0)	1m 14s
install-windows-ucrt (3.3)	1m 52s
test-windows-mingw (2019, 3.0)	5m 12s
test-windows-ucrt (2019, 3.2)	6m 48s
test-windows-mingw (2022, 2.7)	6m 42s
test-windows-ucrt (2019, 3.3)	6m 14s
test-windows-mingw (2022, 3.0)	6m 49s
test-windows-ucrt (2022, 3.1)	6m 7s
test-windows-ucrt (2022, 3.2)	5m 22s
test-windows-ucrt (2022, 3.3)	5m 41s
	1h 48m 33s

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