Update CI

Author: fingolfin

.github/workflows/CI.yml

@@ -37,7 +37,7 @@ jobs:
       - uses: gap-actions/build-pkg-docs@v1
       - uses: gap-actions/run-pkg-tests@v2
       - uses: gap-actions/process-coverage@v2
-      - uses: codecov/codecov-action@v3
+      - uses: codecov/codecov-action@v4
 
   # The documentation job
   manual:
@@ -51,7 +51,7 @@ jobs:
         with:
           use-latex: 'true'
       - name: 'Upload documentation'
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: manual
           path: ./doc/manual.pdf