Bump nl.talsmasoftware:umldoclet from 2.2.0 to 2.2.1 (#239)

Bumps [nl.talsmasoftware:umldoclet](https://github.com/talsma-ict/umldoclet) from 2.2.0 to 2.2.1.
- [Release notes](https://github.com/talsma-ict/umldoclet/releases)
- [Commits](talsma-ict/umldoclet@2.2.0...2.2.1)

---
updated-dependencies:
- dependency-name: nl.talsmasoftware:umldoclet
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pom.xml

@@ -87,7 +87,7 @@
         <jacoco-maven-plugin.version>0.8.12</jacoco-maven-plugin.version>
         <coveralls-maven-plugin.version>4.3.0</coveralls-maven-plugin.version>
         <buildnumber-maven-plugin.version>3.2.1</buildnumber-maven-plugin.version>
-        <umldoclet.version>2.2.0</umldoclet.version>
+        <umldoclet.version>2.2.1</umldoclet.version>
     </properties>
 
     <build>