Make the matrix stop overwriting itself

.github/workflows/build_docs.yml

@@ -86,8 +86,11 @@ jobs:
             echo "::warning title=Invalid file permissions automatically fixed::$line"
           done
 
-      - name: Upload Pages artifact
-        uses: actions/upload-pages-artifact@v2
+      - name: Upload temporary Pages artifact
+        uses: actions/upload-artifact@v3
+        with:
+          name: github-pages-tmp
+          path: _site/
   
   generate:
     runs-on: ubuntu-latest
@@ -118,12 +121,29 @@ jobs:
       - name: Build web book
         run: $HEXDOC --lang ${{ matrix.lang }} -o _site
 
+      - name: Upload temporary Pages artifact
+        uses: actions/upload-artifact@v3
+        with:
+          name: github-pages-tmp
+          path: _site/
+
+  bundle-pages:
+    runs-on: ubuntu-latest
+    needs: generate
+
+    steps:
+      - name: Download temporary Pages artifact
+        uses: actions/download-artifact@v3
+        with:
+          name: github-pages-tmp
+          path: _site/
+
       - name: Upload Pages artifact
         uses: actions/upload-pages-artifact@v2
 
   deploy-pages:
     runs-on: ubuntu-latest
-    needs: generate
+    needs: bundle-pages
 
     environment:
       name: github-pages