TYP: Update pyright
Newer releases of pyright infer return types of partially annotated functions, which uncovers quite a few difficult-to-fix type errors (some functions had no return types because it would create too many typing errors elsewhere).

(pyright can also try to infer return types for completely unannotated functions, but that is disabled for now in pyright_reportGeneralTypeIssues.json  as it would trigger more difficult-to-fix cases.)
Thanks @twoertwein 