GUACAMOLE-1956: Update Duo SDK to latest compatible (1.3.1).

extensions/guacamole-auth-duo/pom.xml

@@ -77,7 +77,7 @@
         <dependency>
             <groupId>com.duosecurity</groupId>
             <artifactId>duo-universal-sdk</artifactId>
-            <version>1.2.0</version>
+            <version>1.3.1</version>
             <exclusions>
                 <exclusion>
                     <groupId>com.squareup.okhttp3</groupId>