style: remove Prettier parser (#45)

Prettier seems to understand the difference between .js, .ts etc.
Maybe this can solve some issues (like the conversion from Yaml to
gibberish with PrettierCI)?

PS: We need this config even if it is completely empty to override
~/.prettierrc.json.

.prettierrc.json

@@ -1,3 +1 @@
-{
-  "parser": "typescript"
-}
+{}