Remove gitmodule for Catch2, replaced it with header file

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "extern/Catch2"]
-	path = extern/Catch2
-	url = git@github.com:catchorg/Catch2.git

CMakeLists.txt

@@ -2,12 +2,12 @@ cmake_minimum_required(VERSION 3.13)
 project(PorygonLang)
 
 set(CMAKE_CXX_STANDARD 17)
-add_subdirectory(extern/Catch2)
+#add_subdirectory(extern)
+include_directories(extern)
 
 add_library(PorygonLang src/main.cpp src/main.h++ src/Parser/Lexer.cpp src/Parser/Lexer.hpp src/Parser/TokenKind.hpp src/Parser/Token.hpp)
 add_executable(PorygonLangTests src/main.cpp src/main.h++ src/Parser/Lexer.cpp src/Parser/Lexer.hpp src/Parser/TokenKind.hpp src/Parser/Token.hpp src/Parser/LexerTests.cpp)
 
-target_link_libraries(PorygonLangTests Catch2::Catch2)
 target_compile_definitions(PorygonLangTests PRIVATE TESTS_BUILD)
 
 

extern/Catch2

@@ -1 +0,0 @@
-Subproject commit e680c4b9fb1d699bfad239e42ce7643d7cf00371

src/Parser/LexerTests.cpp

@@ -1,7 +1,7 @@
 
 #ifdef TESTS_BUILD
 #define CATCH_CONFIG_MAIN
-#include <catch2/catch.hpp>
+#include <catch.hpp>
 #include "Lexer.hpp"
 
 TEST_CASE( "When at end of script return terminator", "[lexer]" ) {