[python] Remove pre-commit/mirrors-prettier hook (#3952)

* Use `rbubley/mirrors-prettier` @ 3.5.3

`pre-commit/mirrors-prettier` was archived, this appears to be a reasonably-maintained and -starred fork, which also only updates vs. full (non-alpha)	prettier` releases

* rm `prettier` pre-commit hook

Author: ryan-williams

.pre-commit-config.yaml

@@ -22,8 +22,3 @@ repos:
         - types-setuptools
       args: ["--config-file=apis/python/pyproject.toml", "apis/python/src", "apis/python/devtools"]
       pass_filenames: false
-  - repo: https://github.com/pre-commit/mirrors-prettier
-    rev: v4.0.0-alpha.8
-    hooks:
-      - id: prettier
-        files: "encoding_specification.md"