chore: run prettier on yml files

Author: vil02

Diff for: .pre-commit-config.yaml

@@ -59,3 +59,9 @@ repos:
           - --install-types # See mirrors-mypy README.md
           - --non-interactive
         additional_dependencies: [types-requests]
+
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: 'v3.1.0'
+    hooks:
+      - id: prettier
+        types: [yaml]