Remove non-text character at start of imgui.cpp

imgui.cpp

@@ -1,4 +1,4 @@
-// ImGui library v1.44 WIP
+// ImGui library v1.44 WIP
 // See ImGui::ShowTestWindow() for sample code.
 // Read 'Programmer guide' below for notes on how to setup ImGui in your codebase.
 // Get latest version at https://github.com/ocornut/imgui