Bump version of GitHub action pr-preview-action and checkout (#7264)

Author: zeme-wana

.github/workflows/broken-links.yml

@@ -10,15 +10,15 @@ on:
   pull_request:
   push:
     branches:
-      master
+      - master
 
 jobs:
   check:
     name: Check
     runs-on: [plutus-ci, self-hosted]
     steps:
       - name: Checkout
-        uses: actions/checkout@main
+        uses: actions/checkout@v4.3.0
 
       - name: Run Linkchecker
         run: |

.github/workflows/docusaurus-site.yml

@@ -27,7 +27,7 @@ jobs:
       name: github-pages
     steps:
       - name: Checkout
-        uses: actions/checkout@main
+        uses: actions/checkout@v4.3.0
 
       - name: Build Site 
         if: github.event_name == 'push' || github.event_name == 'workflow_dispatch'
@@ -47,14 +47,14 @@ jobs:
         working-directory: doc/docusaurus
         run: |
           PR_NUMBER="${{ github.event.pull_request.number }}" 
-          # These match the URL expected by rossjrw/pr-preview-action@v1:
+          # These match the URL expected by rossjrw/pr-preview-action@v1.6.2:
           export DOCUSAURUS_URL="https://plutus.cardano.intersectmbo.org"
           export DOCUSAURUS_BASE_URL="/pr-preview/pr-${PR_NUMBER}"
           nix develop --no-warn-dirty --accept-flake-config --command bash -c 'yarn && yarn build'
 
       - name: Deploy Preview Site 
         if: github.event_name == 'pull_request' && github.event.action != 'closed'
-        uses: rossjrw/pr-preview-action@v1
+        uses: rossjrw/pr-preview-action@v1.6.2
         with:
           source-dir: doc/docusaurus/build