Bump minimalMavenBuildVersion from 3.8.1 to 3.9

Fixes:
[INFO] Project requires minimum Maven version for build of: 3.8.1
[INFO] Plugins require minimum Maven version of: 3.9
[INFO]
[ERROR] Project requires an incorrect minimum version of Maven.
[ERROR] Update the pom.xml to contain maven-enforcer-plugin to
[ERROR] force the Maven version which is needed to build this project.
[ERROR] See
https://maven.apache.org/enforcer/enforcer-rules/requireMavenVersion.html
[ERROR] Using the minimum version of Maven: 3.8.1
[INFO]

Author: garydgregory

pom.xml

@@ -67,7 +67,7 @@
   -->
   <properties>
     <!-- Minimum Maven version required by the plugins -->
-    <minimalMavenBuildVersion>3.8.1</minimalMavenBuildVersion>
+    <minimalMavenBuildVersion>3.9</minimalMavenBuildVersion>
     <!-- Minimum Java version required by build -->
     <minimalJavaBuildVersion>8</minimalJavaBuildVersion>
     <!-- configuration bits for cutting a release candidate, must be overridden by components -->

src/changes/changes.xml

@@ -62,6 +62,7 @@ The <action> type attribute can be add,update,fix,remove.
         <!-- ADD -->
         <!-- UPDATE -->
         <action type="update" dev="ggregory" due-to="Gary Gregory">Bump com.github.siom79.japicmp:japicmp-maven-plugin from 0.25.4 to 0.25.5.</action>
+        <action type="update" dev="ggregory" due-to="Gary Gregory">Bump minimalMavenBuildVersion from 3.8.1 to 3.9.</action>
       </release>
       <release version="98" date="2026-04-03" description="This is a feature and maintenance release. Java 8 or later is required.">
 	    <!-- FIX -->