Bump io.micrometer:micrometer-bom from 1.15.5 to 1.15.6

Bumps [io.micrometer:micrometer-bom](https://github.com/micrometer-metrics/micrometer) from 1.15.5 to 1.15.6.
- [Release notes](https://github.com/micrometer-metrics/micrometer/releases)
- [Commits](micrometer-metrics/micrometer@v1.15.5...v1.15.6)

---
updated-dependencies:
- dependency-name: io.micrometer:micrometer-bom
  dependency-version: 1.15.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

build.gradle

@@ -84,7 +84,7 @@ ext {
     log4jVersion = '2.24.3'
     mailVersion = '2.0.5'
     micrometerTracingVersion = '1.5.6'
-    micrometerVersion = '1.15.5'
+    micrometerVersion = '1.15.6'
     mockitoVersion = '5.17.0'
     mongoDriverVersion = '5.5.2'
     mysqlVersion = '9.3.0'