fix issue #1188 (TestNiftyExamples crash)

Author: stephengold

jme3-testdata/build.gradle

@@ -2,13 +2,9 @@ if (!hasProperty('mainClass')) {
     ext.mainClass = ''
 }
 
-repositories {
-    maven {
-        url 'http://nifty-gui.sourceforge.net/nifty-maven-repo'
-    }
-}
+def niftyVersion = '1.4.3'
 
 dependencies {
-    compile 'lessvoid:nifty-examples:1.4.1'
-    runtime 'com.github.nifty-gui:nifty-style-black:1.4.3'
+    runtime "com.github.nifty-gui:nifty-examples:$niftyVersion"
+    runtime "com.github.nifty-gui:nifty-style-black:$niftyVersion"
 }