Minor drive-by fixes

[cbourjau]

These are some very minor drive-by changes. We were stuck on an older version of mypy due to an upper bound.

The build package was renamed as described here.

[adityagoel4512]

Thanks, not sure why pixi adds an upper-bound by default

[jtilly]

Thanks, not sure why pixi adds an upper-bound by default

I call it the poetry disease. See prefix-dev/pixi#639 for a discussion and prefix-dev/pixi#1516 for the introduction of a fix.

pixi config set pinning-strategy no-pin

or

pixi config set pinning-strategy major

strike me as better options for a library.