Add `bigdecimal` as a dependency #20

Job	Run time
cross-compile-linux	9s
install-windows-native (2.7)	4m 11s
install-windows-native (3.0)	2m 36s
cross-compile-windows (x64-mingw32)	56s
install-windows-native (3.1)	3m 5s
install-macos-m1 (2.7)	56s
cross-compile-windows (x86-mingw32)	47s
install-macos-m1 (3.0)	24s
cross-compile-windows (x64-mingw-ucrt)	59s
install-macos-m1 (3.1)	27s
install-windows-native (3.2)	2m 58s
install-macos-m1 (3.2)	24s
install-windows-native (3.3)	3m 29s
install-macos-m1 (3.3)	25s
test-linux (2017, 2.7)	1m 43s
test-linux (2017, 3.0)	1m 8s
test-linux (2017, 3.1)	1m 19s
test-linux (2017, 3.2)	1m 21s
test-linux (2017, 3.3)	1m 20s
test-linux (2019, 2.7)	1m 51s
test-linux (2019, 3.0)	1m 11s
test-linux (2019, 3.1)	1m 22s
test-linux (2019, 3.2)	1m 9s
test-linux (2019, 3.3)	1m 29s
test-linux (2022, 2.7)	1m 26s
test-linux (2022, 3.0)	1m 19s
test-linux (2022, 3.1)	1m 13s
test-linux (2022, 3.2)	1m 25s
test-linux (2022, 3.3)	1m 24s
test-windows-mingw (2019, 2.7)	3m 44s
test-windows-mingw (2019, 3.0)	1m 52s
install-windows-ucrt (3.1)	1m 2s
test-windows-mingw (2022, 2.7)	4m 59s
install-windows-mingw (2.7)	3m 39s
install-windows-ucrt (3.2)	1m 21s
test-windows-mingw (2022, 3.0)	1m 46s
install-windows-mingw (3.0)	3m 9s
install-windows-ucrt (3.3)	2m 59s
test-windows-ucrt (2019, 3.1)	1m 45s
test-windows-ucrt (2019, 3.2)	2m 16s
test-windows-ucrt (2019, 3.3)	3m 53s
test-windows-ucrt (2022, 3.1)	2m 32s
test-windows-ucrt (2022, 3.2)	2m 14s
test-windows-ucrt (2022, 3.3)	2m 23s
	1h 22m 0s

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