home: git: use 'mkAfter' for config includes

This should ensure that they will be included at the very end of the
configuration. Notably, this ensures that the local configuration can
override any other setting.

modules/home/git/default.nix

@@ -162,7 +162,7 @@ in
       };
     };
 
-    includes = [
+    includes = lib.mkAfter [
       # Multiple identities
       {
         condition = "gitdir:~/git/EPITA/";