v0.20.0

Changelog

• 32e0dc7 refactor: simplify generator tests
• b590b09 feat: pubsub wiring is functional
• 654880e fix: if zero's library is out of date, go get the entire tree
• f365ef9 chore: speed up depgraph tests a bit with a pool of test dirs
• ecd332a refactor: simplify test helpers in depgraph
• af953e3 fix: subscription dependency on topic
• 2712110 chore: figure out bug
• 97677f4 feat: code generation for pubsub
• 723562e refactor: pubsub API now exposes Event[T] directly
• 99b9811 chore: mark all tests that can be, as t.Parallel()
• 1277ee0 feat: update depgraph to extract subscriber methods
• 2ae635d feat: add parser for //zero:subscribe directive
• 24f7231 fix: validate that provided root types exist (#13)