Add missing imgui submodule URL to .gitmodules

Author: andrestraker

.gitmodules

@@ -6,6 +6,6 @@
 	path = ToF-drivers
 	url = https://github.com/analogdevicesinc/ToF-drivers.git
 	branch = dev-6.2.0
-[submodule "dependencies/third-party/imgui2/imgui"]
+[submodule "dependencies/third-party/imgui/imgui"]
 	path = dependencies/third-party/imgui/imgui
 	url = https://github.com/ocornut/imgui.git