remove deprecation warnings / errors on junit4/ build

Reason: It still supports the old and deprecated junit4/ API such that
it still needs to use it in order to provide the features using it

Signed-off-by: Andreas Schmid <service@aaschmid.de>

build.gradle

@@ -129,7 +129,7 @@ project(':junit4') {
     }
 
     tasks.withType(JavaCompile) {
-        options.compilerArgs += [ '-Xlint:-options' ]
+        options.compilerArgs += [ '-Xlint:-options', '-Xlint:-deprecation' ]
     }
 
     jar {