Auto merge of rust-lang#935 - bradfier:bump, r=emilio

Bump version to 0.30.0

Version bump, primarily to get rust-lang#832 and rust-lang#892 in now that 1.19 is out and untagged unions are usable in stable!

r? @emilio

Auto merge of rust-lang#721 - fitzgen:bump-to-0.25.2, r=emilio

Bump to version 0.25.2

Need to publish a new version so I can rely on the MacOS mangling fix for my smup branch.

r? @emilio