Updated ExternalProject with GIT_SHALLOW

For the prepare_catch file, the external projects now have GIT_SHALLOW
enabled, so that the repository only pulls the repository with a
`--depth 1` value, limiting what is pulled in to the minimum required.

Author: StableCoder

prepare_catch.cmake

@@ -63,6 +63,7 @@ function(prepare_catch)
           git_catch
           PREFIX ${CMAKE_BINARY_DIR}/catch2
           GIT_REPOSITORY https://github.com/catchorg/Catch2.git
+          GIT_SHALLOW 1
           TIMEOUT 10
           UPDATE_COMMAND ${GIT_EXECUTABLE} pull
           CONFIGURE_COMMAND ""
@@ -76,6 +77,7 @@ function(prepare_catch)
           PREFIX ${CMAKE_BINARY_DIR}/catch1
           GIT_REPOSITORY https://github.com/catchorg/Catch2.git
           GIT_TAG Catch1.x
+          GIT_SHALLOW 1
           TIMEOUT 10
           UPDATE_COMMAND ${GIT_EXECUTABLE} pull
           CONFIGURE_COMMAND ""