Bump version to 3.1.9-WHO

Author: github-actions[bot]

pom.xml

@@ -14,7 +14,7 @@
     <description>This library defines an API for the webprotege-backend service</description>
     <groupId>edu.stanford.protege</groupId>
     <artifactId>webprotege-backend-api</artifactId>
-    <version>3.1.8-WHO</version>
+    <version>3.1.9-WHO</version>
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>