Update the external actions in the deploy-to-gh-pages workflow.

Author: sjrd

.github/workflows/ghpages.yml

@@ -10,12 +10,11 @@ jobs:
   build-and-deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: olafurpg/setup-scala@v5
-
-      - name: Checkout
-        uses: actions/[email protected]
+      - uses: actions/checkout@v2
+      - uses: olafurpg/setup-scala@v10
         with:
-          persist-credentials: false
+          java-version: "[email protected]"
+      - uses: coursier/cache-action@v5
 
       - name: Build
         run: sbt readme/run