.github/workflows/sphinx: update workflow file to latest standard

.github/workflows/sphinx.yml

@@ -4,6 +4,7 @@
 # License: CC-0.  This is the canonical location of this file, which
 # you may want to link to anyway:
 #   https://github.com/coderefinery/sphinx-lesson-template/blob/main/.github/workflows/sphinx.yml
+#  https://raw.githubusercontent.com/coderefinery/sphinx-lesson-template/main/.github/workflows/sphinx.yml
 
 
 name: sphinx
@@ -14,7 +15,8 @@ env:
   # If these SPHINXOPTS are enabled, then be strict about the
   # builds and fail on any warnings.
   #SPHINXOPTS: "-W --keep-going -T"
-  GENERATE_PDF: true   # to enable, must be 'true' lowercase
+  GENERATE_PDF: true          # to enable, must be 'true' lowercase
+  GENERATE_SINGLEHTML: true   # to enable, must be 'true' lowercase
   PDF_FILENAME: lesson.pdf
   MULTIBRANCH: true    # to enable, must be 'true' lowercase
 
@@ -61,6 +63,7 @@ jobs:
           echo "github.head_ref: ${head_ref}"
           echo "github.base_ref: ${base_ref}"
           echo "GENERATE_PDF: ${GENERATE_PDF}"
+          echo "GENERATE_SINGLEHTML: ${GENERATE_SINGLEHTML}"
           set -x
           git rev-parse --abbrev-ref HEAD
           git branch
@@ -88,6 +91,7 @@ jobs:
 
       # singlehtml
       - name: Generate singlehtml
+        if: ${{ env.GENERATE_SINGLEHTML == 'true' }}
         run: |
           make singlehtml
           mv _build/singlehtml/ _build/dirhtml/singlehtml/
@@ -125,7 +129,7 @@ jobs:
           touch _gh-pages/.nojekyll
 
       # Save artifact for the next step.
-      - uses: actions/upload-artifact@master
+      - uses: actions/upload-artifact@v4
         if: ${{ github.event_name == 'push' }}
         with:
           name: gh-pages-build
@@ -143,7 +147,7 @@ jobs:
       contents: write
 
     steps:
-      - uses: actions/download-artifact@v3
+      - uses: actions/download-artifact@v4
         if: ${{ github.event_name == 'push' && ( env.MULTIBRANCH == 'true' || github.ref == format('refs/heads/{0}', env.DEFAULT_BRANCH )) }}
         with:
           name: gh-pages-build