Add `bigdecimal` as a dependency #16

Job	Run time
cross-compile-windows (x64-mingw32)	6m 1s
cross-compile-windows (x86-mingw32)	5m 4s
cross-compile-windows (x64-mingw-ucrt)	6m 4s
install-windows-native (2.7)	3m 59s
install-macos-m1 (2.7)	38s
install-windows-native (3.0)	2m 14s
cross-compile-linux	3m 18s
install-macos-m1 (3.0)	25s
install-windows-native (3.1)	2m 39s
install-windows-native (3.2)	2m 25s
install-macos-m1 (3.1)	27s
install-windows-native (3.3)	3m 35s
install-macos-m1 (3.2)	26s
install-macos-m1 (3.3)	30s
test-linux (2017, 2.7)	1m 32s
test-linux (2017, 3.0)	1m 18s
test-linux (2017, 3.1)	1m 20s
test-linux (2017, 3.2)	1m 55s
test-linux (2017, 3.3)	1m 11s
test-linux (2019, 2.7)	1m 23s
test-linux (2019, 3.0)	1m 19s
test-linux (2019, 3.1)	1m 17s
test-linux (2019, 3.2)	1m 22s
test-linux (2019, 3.3)	1m 17s
test-linux (2022, 2.7)	1m 26s
test-linux (2022, 3.0)	1m 18s
test-linux (2022, 3.1)	1m 31s
test-linux (2022, 3.2)	1m 18s
test-linux (2022, 3.3)	1m 10s
install-windows-mingw (2.7)	2m 44s
install-windows-ucrt (3.1)	1m 25s
test-windows-ucrt (2019, 3.1)	2m 1s
install-windows-mingw (3.0)	1m 33s
install-windows-ucrt (3.2)	1m 38s
test-windows-mingw (2019, 2.7)	3m 9s
test-windows-ucrt (2019, 3.2)	55s
install-windows-ucrt (3.3)	3m 23s
test-windows-ucrt (2019, 3.3)	1m 37s
test-windows-mingw (2019, 3.0)	53s
test-windows-ucrt (2022, 3.1)	1m 26s
test-windows-mingw (2022, 2.7)	2m 33s
test-windows-ucrt (2022, 3.2)	1m 0s
test-windows-mingw (2022, 3.0)	1m 0s
test-windows-ucrt (2022, 3.3)	3m 11s
	1h 26m 50s

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