chore: regenerate from opentelemetry-proto v1.8.0 (#1921)

* chore: regenerate from opentelemetry-proto v1.8.0

* Update exporter/otlp/Rakefile

Co-authored-by: Robert <[email protected]>

---------

Co-authored-by: Robert <[email protected]>

Author: fbogsany

exporter/otlp/Rakefile

@@ -32,8 +32,8 @@ default_tasks =
 
 task default: default_tasks
 
-# https://github.com/open-telemetry/opentelemetry-proto/tree/v0.20.0
-PROTO_VERSION = 'v0.20.0'
+# https://github.com/open-telemetry/opentelemetry-proto/tree/v1.8.0
+PROTO_VERSION = 'v1.8.0'
 
 namespace :protobuf do
   desc 'Remove proto file'