Bump de.jflex:jflex-maven-plugin from 1.8.2 to 1.9.1

Bumps [de.jflex:jflex-maven-plugin](https://github.com/jflex-de/jflex) from 1.8.2 to 1.9.1.
- [Release notes](https://github.com/jflex-de/jflex/releases)
- [Changelog](https://github.com/jflex-de/jflex/blob/master/RELEASE.md)
- [Commits](jflex-de/jflex@v1.8.2...v1.9.1)

---
updated-dependencies:
- dependency-name: de.jflex:jflex-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -247,7 +247,7 @@
       <plugin>
         <groupId>de.jflex</groupId>
         <artifactId>jflex-maven-plugin</artifactId>
-        <version>1.8.2</version>
+        <version>1.9.1</version>
         <executions>
           <execution>
             <goals>