chore(gradle): bump org.assertj:assertj-core from 3.19.0 to 3.26.3

Bumps [org.assertj:assertj-core](https://github.com/assertj/assertj) from 3.19.0 to 3.26.3.
- [Release notes](https://github.com/assertj/assertj/releases)
- [Commits](assertj/assertj@assertj-core-3.19.0...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] <support@github.com>

gradle/libs.versions.toml

@@ -82,7 +82,7 @@ vertispan-ts-defs = "1.0.0-RC4"
 xerial = "3.46.1.3"
 
 # test versions
-assertj = "3.19.0"
+assertj = "3.26.3"
 h2database = "2.2.224"
 jmock = "2.13.1"
 junit = "5.7.2"