chore: have Prettier format all allowed file types

Author: Emanuel Kluge

.prettierignore

@@ -5,3 +5,4 @@ fragmentTypes.json
 **/package.json
 CHANGELOG.md
 packages/*/CHANGELOG.md
+coverage

package.json

@@ -39,7 +39,7 @@
     "release:rc": "yarn release --conventional-prerelease --preid rc",
     "release:graduate": "yarn release --conventional-graduate",
     "reset": "git clean -dfx && yarn",
-    "fmt": "prettier --write '**/*.{js,json,css}' '**/README.md'"
+    "fmt": "prettier --write --ignore-unknown ."
   },
   "canarist": {
     "projects": [