CI: upload manual.pdf uncompressed

Makes it more convenient to inspect it on GitHub

Author: fingolfin

.github/workflows/docs.yml

@@ -28,8 +28,8 @@ jobs:
         with:
           use-latex: 'true'
       - name: 'Upload documentation'
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
-          name: manual
+          archive: false
           path: ./doc/manual.pdf
           if-no-files-found: error