bump proto to 0.9.0 (open-telemetry#1873)

Author: alrex

CHANGELOG.md

@@ -19,6 +19,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#1869](https://github.com/open-telemetry/opentelemetry-python/pull/1869))
 - Added optional `schema_url` field to `Resource` class
   ([#1871](https://github.com/open-telemetry/opentelemetry-python/pull/1871))
+- Update protos to latest version release 0.9.0
+  ([#1873](https://github.com/open-telemetry/opentelemetry-python/pull/1873))
 
 ## [1.2.0, 0.21b0](https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.2.0-0.21b0) - 2021-05-11