Update upload-artifact version in ci

Author: MaximilianAlgehed

.github/workflows/ci.yaml

@@ -87,7 +87,7 @@ jobs:
         nix develop --accept-flake-config --command .github/workflows/ci-haddock.sh
 
     - name: Upload build & test artifacts
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v3
       with:
         name: haddocks
         path: ./docs