Pin Hugo version in GitHub Actions

.github/workflows/gh-pages.yml

@@ -6,6 +6,7 @@ on:
     branches:
       - master
   pull_request:
+  workflow_dispatch:
 
 jobs:
   deploy:
@@ -18,7 +19,11 @@ jobs:
           fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod
 
       - name: Install Hugo
-        run: sudo snap install hugo
+        env:
+          HUGO_VERSION: 0.123.0
+        run: |
+          wget -O ${{ runner.temp }}/hugo.deb https://github.com/gohugoio/hugo/releases/download/v${HUGO_VERSION}/hugo_extended_${HUGO_VERSION}_linux-amd64.deb \
+          && sudo dpkg -i ${{ runner.temp }}/hugo.deb
 
       - name: Build production site
         run: hugo --minify
@@ -30,7 +35,7 @@ jobs:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./public
 
-      # The following steps aren't essentially, but useful for debugging and viewing a human-friendly diff.
+      # The following steps aren't essential, but useful for debugging and viewing a human-friendly diff.
       - name: Rebuild site without minification (master only)
         if: github.ref == 'refs/heads/master'
         run: hugo --destination ./public-unminified