Bump org.assertj:assertj-core from 3.27.4 to 3.27.6 in /modules/r2dbc

Bumps [org.assertj:assertj-core](https://github.com/assertj/assertj) from 3.27.4 to 3.27.6.
- [Release notes](https://github.com/assertj/assertj/releases)
- [Commits](assertj/assertj@assertj-build-3.27.4...assertj-build-3.27.6)

---
updated-dependencies:
- dependency-name: org.assertj:assertj-core
  dependency-version: 3.27.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

modules/r2dbc/build.gradle

@@ -12,6 +12,6 @@ dependencies {
     testImplementation project(':testcontainers-postgresql')
 
     testFixturesImplementation 'io.projectreactor:reactor-core:3.7.11'
-    testFixturesImplementation 'org.assertj:assertj-core:3.27.4'
+    testFixturesImplementation 'org.assertj:assertj-core:3.27.6'
     testFixturesImplementation 'org.junit.jupiter:junit-jupiter:5.13.4'
 }