Remove all other submodules

Author: k3DW

.gitmodules

@@ -1,15 +1,3 @@
-[submodule "external/wxWidgets"]
-	path = external/wxWidgets
-	url = https://github.com/wxWidgets/wxWidgets.git
-[submodule "external/mdspan"]
-	path = external/mdspan
-	url = https://github.com/kokkos/mdspan.git
-[submodule "external/glew"]
-	path = external/glew
-	url = https://github.com/PartStackerCommunity/glew.git
-[submodule "external/Catch2"]
-	path = external/Catch2
-	url = https://github.com/catchorg/Catch2.git
 [submodule "external/vcpkg"]
 	path = external/vcpkg
 	url = https://github.com/microsoft/vcpkg.git