Mod/Complete: suppress a minor warning

The warning was dedicated to using of char as an array index.

src/Mod/Complete/Gui/AppCompleteGui.cpp

@@ -64,7 +64,7 @@ void CompleteGuiExport initCompleteGui()
     // try to load dependent modules, currently not (AssemblyGui, CamGui)
     char *modules[] = {"PartGui", "MeshGui", "MeshPartGui", "PointsGui", "DrawingGui", "RaytracingGui", "SketcherGui", "PartDesignGui", "ImageGui", "TestGui"};
     char nModules = sizeof(modules) / sizeof(char*);
-    for (char i = 0; i < nModules; i++) {
+    for (size_t i = 0; i < nModules; i++) {
         try {
             Base::Interpreter().loadModule(modules[i]);
         }