externals: Update catch to 2.3.0

Updates the library from 2.2.3 to 2.3.0

src/tests/tests.cpp

@@ -3,7 +3,7 @@
 // Refer to the license.txt file included.
 
 #define CATCH_CONFIG_MAIN
-#include <catch.hpp>
+#include <catch2/catch.hpp>
 
 // Catch provides the main function since we've given it the
 // CATCH_CONFIG_MAIN preprocessor directive.