remove obsolete pr template

.github/pull_request_template.md

@@ -1,12 +0,0 @@
-<!--
-- Recipes should be `.md` files in the `src/` directory.  Look at already
-  existing `.md` files for examples or see [example](example.md).
-- File names should be the name of the dish with words separated by hyphens
-  (`-`). Not underscores, and definitely not spaces.
-- Recipe must be based, i.e. good traditional and substantial food. Nothing
-  ironic, meme-tier hyper-sugary, meat-substitute, etc.
-- Be sure to add a small number of relevant  tags to your recipe (and remove
-  the dummy tags). Try to use already existing tags.
-- Don't include salt and pepper and other ubiquitous things in the ingredients
-  list.
--->