ci: fix "Update Prettier" workflow (#284)

* ci: fix branch name for "Update Prettier" workflow

The workflow broke when we switched from Dependabot to Renovate

* build(deps): pin prettier version

Author: wolfy1339

.github/workflows/update-prettier.yml

@@ -2,7 +2,7 @@ name: Update Prettier
 "on":
   push:
     branches:
-      - dependabot/npm_and_yarn/prettier-*
+      - renovate/prettier-*
 jobs:
   update_prettier:
     runs-on: ubuntu-latest

package.json

@@ -38,7 +38,7 @@
     "@types/node": "^14.0.4",
     "fetch-mock": "^9.0.0",
     "jest": "^27.0.0",
-    "prettier": "^2.0.0",
+    "prettier": "2.3.0",
     "semantic-release": "^17.0.0",
     "semantic-release-plugin-update-version-in-files": "^1.0.0",
     "ts-jest": "^27.0.0-next.12",