Fixed typo in VariablesResource POST /variables

Author: anthonygauthier

src/main/java/io/github/delirius325/jmeter/config/livechanges/api/resources/VariablesResource.java

@@ -65,7 +65,7 @@ public Response postVariables(String request) {
             }
         });
         LiveChanges.setjMeterVariables(vars);
-        JSONHelper.jsonSetInfo(json, "success", "VariablesResource were changed.");
+        JSONHelper.jsonSetInfo(json, "success", "Variables were changed.");
         return Response.ok(json.toString()).build();
     }
 }