Bump io.opentelemetry.instrumentation:opentelemetry-instrumentation-b…

…om-alpha

Bumps [io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom-alpha](https://github.com/open-telemetry/opentelemetry-java-instrumentation) from 2.7.0-alpha to 2.9.0-alpha.
- [Release notes](https://github.com/open-telemetry/opentelemetry-java-instrumentation/releases)
- [Changelog](https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/CHANGELOG.md)
- [Commits](https://github.com/open-telemetry/opentelemetry-java-instrumentation/commits)

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

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

getting-started-guides/java/build.gradle

@@ -27,7 +27,7 @@ configurations {
   agent
 }
 
-def otelInstrumentationVersion = "2.7.0-alpha";
+def otelInstrumentationVersion = "2.9.0-alpha";
 
 dependencies {
   implementation platform(SpringBootPlugin.BOM_COORDINATES)