Bump org.assertj:assertj-core in /modules/cockroachdb

Bumps [org.assertj:assertj-core](https://github.com/assertj/assertj) from 3.25.3 to 3.26.3.
- [Release notes](https://github.com/assertj/assertj/releases)
- [Commits](assertj/assertj@assertj-build-3.25.3...assertj-build-3.26.3)

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

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

Author: dependabot[bot]

modules/cockroachdb/build.gradle

@@ -5,5 +5,5 @@ dependencies {
 
     testImplementation project(':jdbc-test')
     testRuntimeOnly 'org.postgresql:postgresql:42.7.3'
-    testImplementation 'org.assertj:assertj-core:3.25.3'
+    testImplementation 'org.assertj:assertj-core:3.26.3'
 }