Bump junit-bom from 5.9.0 to 5.9.1

Bumps [junit-bom](https://github.com/junit-team/junit5) from 5.9.0 to 5.9.1.
- [Release notes](https://github.com/junit-team/junit5/releases)
- [Commits](https://github.com/junit-team/junit5/compare/r5.9.0...r5.9.1)

---
updated-dependencies:
- dependency-name: org.junit:junit-bom
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle

@@ -29,7 +29,7 @@ allprojects {
     ext {
         nanojsonVersion = "1d9e1aea9049fc9f85e68b43ba39fe7be1c1f751"
         spotbugsVersion = "4.7.1"
-        junitVersion = "5.9.0"
+        junitVersion = "5.9.1"
         checkstyleVersion = "9.3" // do not use latest version (10.0) as it requires compile JDK 11
     }
 }