workflows: run prettier as part of changeset versioning

.github/workflows/changeset.yml

@@ -15,5 +15,8 @@ jobs:
         run: yarn --frozen-lockfile
       - name: Create Release Pull Request
         uses: changesets/action@master
+        with:
+          # Calls out to `changeset version`, but also runs prettier
+          version: yarn version
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

package.json

@@ -28,7 +28,8 @@
     "prettier:check": "prettier --check .",
     "lerna": "lerna",
     "storybook": "yarn workspace storybook start",
-    "build-storybook": "yarn workspace storybook build-storybook"
+    "build-storybook": "yarn workspace storybook build-storybook",
+    "version": "changeset version && yarn prettier --write '{packages,plugins}/*/{package.json,CHANGELOG.md}'"
   },
   "workspaces": {
     "packages": [