Bump google.golang.org/protobuf in /exporters/otlp/otlptrace

Bumps [google.golang.org/protobuf](https://github.com/protocolbuffers/protobuf-go) from 1.27.1 to 1.28.0.
- [Release notes](https://github.com/protocolbuffers/protobuf-go/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf-go/blob/master/release.bash)
- [Commits](protocolbuffers/protobuf-go@v1.27.1...v1.28.0)

---
updated-dependencies:
- dependency-name: google.golang.org/protobuf
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

exporters/otlp/otlptrace/go.mod

@@ -11,7 +11,7 @@ require (
 	go.opentelemetry.io/otel/trace v1.6.0
 	go.opentelemetry.io/proto/otlp v0.12.0
 	google.golang.org/grpc v1.45.0
-	google.golang.org/protobuf v1.27.1
+	google.golang.org/protobuf v1.28.0
 )
 
 replace go.opentelemetry.io/otel => ../../..

exporters/otlp/otlptrace/go.sum

@@ -130,6 +130,8 @@ google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp0
 google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
 google.golang.org/protobuf v1.27.1 h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
 google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.28.0 h1:w43yiav+6bVFTBQFZX0r7ipe9JQ1QsbMgHwbBziscLw=
+google.golang.org/protobuf v1.28.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=