chore: bump org.assertj:assertj-core in /powertools-metrics

Bumps [org.assertj:assertj-core](https://github.com/assertj/assertj) from 3.27.6 to 3.27.7.
- [Release notes](https://github.com/assertj/assertj/releases)
- [Commits](assertj/assertj@assertj-build-3.27.6...assertj-build-3.27.7)

---
updated-dependencies:
- dependency-name: org.assertj:assertj-core
  dependency-version: 3.27.7
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pom.xml

@@ -335,7 +335,7 @@
             <dependency>
                 <groupId>org.assertj</groupId>
                 <artifactId>assertj-core</artifactId>
-                <version>3.27.6</version>
+                <version>3.27.7</version>
                 <scope>test</scope>
                 <exclusions>
                     <exclusion>