deps: update fmt to latest version (#3403)

This updates `fmt` to the latest version and moves to just being a copy
of their repo to make updating easier (no editing their cmake / figuring
out which files to minimally include).

The motivation for this is now that we switched to C++ 20, there were a
ton of deprecated function usages that is going away in future compiler
versions. This gets rid of all those warnings.

tools/level_tools/level_dump/main.cpp

@@ -8,7 +8,7 @@
 #include "decompiler/level_extractor/BspHeader.h"
 #include "decompiler/util/goal_data_reader.h"
 
-#include "third-party/fmt/core.h"
+#include "fmt/core.h"
 
 constexpr GameVersion kGameVersion = GameVersion::Jak1;