Revert "Remove flymake mypy (from flymake-collection)"

This reverts commit eb69c67a5d.

config/ide.org

@@ -145,6 +145,11 @@ Set treesit to fontify all elements, default was 3 (out of 4)
     :diminish
     :defer
     :after flymake)
+
+  (with-eval-after-load 'python
+    (add-hook 'python-base-mode-hook
+              (defun python-mode-setup-flymake ()
+                (add-hook 'flymake-diagnostic-functions 'flymake-collection-mypy nil t))))
 #+end_src
 
 ** shellcheck