Bump io.opentelemetry.proto:opentelemetry-proto (#6686)

Bumps [io.opentelemetry.proto:opentelemetry-proto](https://github.com/open-telemetry/opentelemetry-proto-java) from 1.7.0-alpha to 1.8.0-alpha.
- [Release notes](https://github.com/open-telemetry/opentelemetry-proto-java/releases)
- [Commits](https://github.com/open-telemetry/opentelemetry-proto-java/commits)

---
updated-dependencies:
- dependency-name: io.opentelemetry.proto:opentelemetry-proto
  dependency-version: 1.8.0-alpha
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -181,7 +181,7 @@ newrelicApi = { module = "com.newrelic.agent.java:newrelic-api", version.ref = "
 nullAway = { module = "com.uber.nullaway:nullaway", version = "0.12.9" }
 okhttp = { module = "com.squareup.okhttp3:okhttp", version.ref = "okhttp" }
 # some proto are marked alpha, hence the alpha version. metrics proto is what we use and it is marked stable
-openTelemetry-proto = { module = "io.opentelemetry.proto:opentelemetry-proto", version = "1.7.0-alpha" }
+openTelemetry-proto = { module = "io.opentelemetry.proto:opentelemetry-proto", version = "1.8.0-alpha" }
 osgiJunit5 = "org.osgi:org.osgi.test.junit5:1.3.0"
 postgre = { module = "org.postgresql:postgresql", version.ref = "postgre" }
 prometheusMetricsBom = { module = "io.prometheus:prometheus-metrics-bom", version.ref = "prometheus" }