Bump dc-model from 9.1.0 to 9.1.1

Bumps [dc-model](https://github.com/dbmdz/digitalcollections-model) from 9.1.0 to 9.1.1.
- [Release notes](https://github.com/dbmdz/digitalcollections-model/releases)
- [Changelog](https://github.com/dbmdz/digitalcollections-model/blob/main/CHANGELOG.md)
- [Commits](dbmdz/digitalcollections-model@9.1.0...9.1.1)

---
updated-dependencies:
- dependency-name: de.digitalcollections.model:dc-model
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

pom.xml

@@ -82,7 +82,7 @@
     <version.dc-commons-server>4.1.1</version.dc-commons-server>
     <version.dc-commons-springboot>4.1.1</version.dc-commons-springboot>
     <version.dc-commons-springmvc>4.1.2</version.dc-commons-springmvc>
-    <version.dc-model>9.1.0</version.dc-model>
+    <version.dc-model>9.1.1</version.dc-model>
     <version.guava>31.0.1-jre</version.guava>
     <version.iiif-apis>0.3.9</version.iiif-apis>
     <version.imageio-jnr>0.6.2</version.imageio-jnr>