Bump checkstyle from 9.0.1 to 9.1

Bumps [checkstyle](https://github.com/checkstyle/checkstyle) from 9.0.1 to 9.1.
- [Release notes](https://github.com/checkstyle/checkstyle/releases)
- [Commits](checkstyle/checkstyle@checkstyle-9.0.1...checkstyle-9.1)

---
updated-dependencies:
- dependency-name: com.puppycrawl.tools:checkstyle
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -632,7 +632,7 @@
     <commons.encoding>utf-8</commons.encoding>
 
     <checkstyle.plugin.version>3.1.2</checkstyle.plugin.version>
-    <checkstyle.version>9.0.1</checkstyle.version>
+    <checkstyle.version>9.1</checkstyle.version>
     <checkstyle.configdir>src/site/resources/checkstyle</checkstyle.configdir>
 
     <spotbugs.plugin.version>4.4.2.2</spotbugs.plugin.version>

src/changes/changes.xml

@@ -97,7 +97,7 @@ The <action> type attribute can be add,update,fix,remove.
     <action                   type="update" dev="ggregory" due-to="Dependabot, XenoAmess">Bump Bump actions/cache from v2.1.4 to v2.1.6 #742, #752, #764.</action>
     <action                   type="update" dev="ggregory" due-to="Gary Gregory">Bump actions/setup-java from v1.4.3 to v2.</action>
     <action                   type="update" dev="ggregory" due-to="Dependabot">Bump spotbugs from 4.2.2 to 4.2.3 #744.</action>
-    <action                   type="update" dev="ggregory" due-to="Dependabot, Gary Gregory">Bump checkstyle from 8.41 to 9.0.1 #739, #768, #787, #811.</action>
+    <action                   type="update" dev="ggregory" due-to="Dependabot, Gary Gregory">Bump checkstyle from 8.41 to 9.1 #739, #768, #787, #811, #824.</action>
     <action                   type="update" dev="ggregory" due-to="Dependabot">Bump easymock from 4.2 to 4.3 #746.</action>
     <action                   type="update" dev="ggregory" due-to="Gary Gregory">commons.jacoco.version 0.8.6 -> 0.8.7.</action>
     <action                   type="update" dev="ggregory" due-to="Gary Gregory">commons.japicmp.version 0.15.2 -> 0.15.3.</action>