Assorted MyPy improvments #1242

Job	Run time
Build wheel and source distribution	20s
Binary aarch64-unknown-linux-gnu (ubuntu-22.04)	1m 39s
Publish to PyPI	0s
Binary x86_64-unknown-linux-gnu (ubuntu-22.04)	1m 37s
Binary x86_64-unknown-linux-musl (ubuntu-22.04)	1m 43s
Binary powerpc64le-unknown-linux-gnu (ubuntu-22.04)	1m 37s
Binary x86_64-pc-windows-msvc (windows-2022)	1m 32s
Binary i686-pc-windows-msvc (windows-2022)	1m 31s
Binary aarch64-apple-darwin (macos-12)	1m 39s
Binary x86_64-apple-darwin (macos-12)	1m 33s
Build release distributions	0s
Build development distributions	1s
Build macOS installer and sign/notarize artifacts	1s
Build Windows installers	1s
Publish distributions	1s
	13m 15s

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