Update actions/upload-pages-artifact action to v4 (#196)

Author: renovate[bot]

.github/workflows/docs.yaml

@@ -37,7 +37,7 @@ jobs:
           cp -R langchain4j-kotlin/target/dokka target/docs/api
 
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
         with:
           path: target/docs/
       - name: Deploy to GitHub Pages