maven.adoc: JME v3.4.0-stable has been released

docs/modules/ROOT/pages/getting-started/maven.adoc

@@ -51,7 +51,7 @@ repositories {
     mavenCentral()
 }
 
-def jme3 = [v:'3.3.2-stable', g:'org.jmonkeyengine']
+def jme3 = [v:'3.4.0-stable', g:'org.jmonkeyengine']
 dependencies {
     implementation "${jme3.g}:jme3-core:${jme3.v}"
     runtimeOnly "${jme3.g}:jme3-desktop:${jme3.v}"
@@ -65,7 +65,7 @@ dependencies {
 ----
   <properties>
     <jme3_g>org.jmonkeyengine</jme3_g>
-    <jme3_v>3.3.2-stable</jme3_v>
+    <jme3_v>3.4.0-stable</jme3_v>
   </properties>
 
   <repositories>