Change Prettier settings (#36)

## Summary

I know this is a little tedious but I'd prefer to use the same settings
as in Ruff.

.prettierrc.json

@@ -1,11 +1,4 @@
 {
-  "printWidth": 80,
-  "tabWidth": 2,
-  "useTabs": false,
-  "semi": false,
-  "singleQuote": true,
-  "trailingComma": "none",
-  "bracketSpacing": false,
-  "arrowParens": "avoid",
+  "trailingComma": "all",
   "proseWrap": "always"
 }