Bump fluency.version from 2.7.0 to 2.7.3

Bumps `fluency.version` from 2.7.0 to 2.7.3.

Updates `org.komamitsu:fluency-core` from 2.7.0 to 2.7.3
- [Release notes](https://github.com/komamitsu/fluency/releases)
- [Changelog](https://github.com/komamitsu/fluency/blob/master/CHANGELOG.md)
- [Commits](komamitsu/fluency@2.7.0...2.7.3)

Updates `org.komamitsu:fluency-fluentd` from 2.7.0 to 2.7.3
- [Release notes](https://github.com/komamitsu/fluency/releases)
- [Changelog](https://github.com/komamitsu/fluency/blob/master/CHANGELOG.md)
- [Commits](komamitsu/fluency@2.7.0...2.7.3)

---
updated-dependencies:
- dependency-name: org.komamitsu:fluency-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.komamitsu:fluency-fluentd
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

pom.xml

@@ -31,7 +31,7 @@
 
         <mock-slave.version>125.vcfb_5c627d399</mock-slave.version>
         <unique-id.version>2.101.v21a_b_6390a_b_04</unique-id.version>
-        <fluency.version>2.7.0</fluency.version>
+        <fluency.version>2.7.3</fluency.version>
         <jsr305.version>3.0.2</jsr305.version>
     </properties>
     <name>Pipeline Logging via Elasticsearch</name>