Bump splunk-opentelemetry from 2.1.0 to 2.3.0 (#624)

Bumps [splunk-opentelemetry](https://github.com/signalfx/splunk-otel-python) from 2.1.0 to 2.3.0.
- [Release notes](https://github.com/signalfx/splunk-otel-python/releases)
- [Changelog](https://github.com/signalfx/splunk-otel-python/blob/main/CHANGELOG.md)
- [Commits](https://github.com/signalfx/splunk-otel-python/commits)

---
updated-dependencies:
- dependency-name: splunk-opentelemetry
  dependency-version: 2.3.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

docker/requirements.txt

@@ -1 +1 @@
-splunk-opentelemetry==2.1.0
+splunk-opentelemetry==2.3.0