lib-v0.9.0

What's Changed

• Fix is_set by @AdrienVannson in #138
• Make grpclib truly optional by @AdrienVannson in #139
• Format protofiles using Buf by @AdrienVannson in #143
• Fix typechecking import by @AdrienVannson in #145
• Simplify test by @AdrienVannson in #146
• Bump to 0.9.0 by @AdrienVannson in #147

Full Changelog: compiler-v0.8.0...lib-v0.9.0