Bump proc-macro2 from 0.4.29 to 0.4.30 (#527)
Bump proc-macro2 from 0.4.29 to 0.4.30 (#527)

Bumps [proc-macro2](https://github.com/alexcrichton/proc-macro2) from 0.4.29 to 0.4.30.
- [Release notes](https://github.com/alexcrichton/proc-macro2/releases)
- [Commits](https://github.com/alexcrichton/proc-macro2/compare/0.4.29...0.4.30)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust