fix(deps): update otel.instrumentation.version (#2236)

This PR contains the following updates:

| Package | Change |
[Age](https://docs.renovatebot.com/merge-confidence/) |
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[io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom-alpha](https://redirect.github.com/open-telemetry/opentelemetry-java-instrumentation)
| `2.28.1-alpha` → `2.29.0-alpha` |
![age](https://developer.mend.io/api/mc/badges/age/maven/io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom-alpha/2.29.0-alpha?slim=true)
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docs/apidiffs/current_vs_latest/prometheus-metrics-exporter-opentelemetry-shaded.txt

@@ -26,7 +26,7 @@
     <awaitility.version>4.3.0</awaitility.version>
     <wiremock.version>3.13.2</wiremock.version>
     <junit-jupiter.version>6.1.0</junit-jupiter.version>
-    <otel.instrumentation.version>2.28.1-alpha</otel.instrumentation.version>
+    <otel.instrumentation.version>2.29.0-alpha</otel.instrumentation.version>
     <java.version>8</java.version>
     <test.java.version>25</test.java.version>
     <!-- Bumped by .github/workflows/bump-api-diff-baseline.yml after each release. -->