fix: packages/documentation-site/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-ECHARTS-16874133

Author: snyk-bot

packages/documentation-site/package.json

@@ -34,7 +34,7 @@
     "@patternfly/react-user-feedback": "6.3.0",
     "@patternfly/react-virtualized-extension": "6.2.0",
     "@xyflow/react": "^12.10.1",
-    "echarts": "^5.6.0",
+    "echarts": "^6.1.0",
     "file-saver": "^2.0.5",
     "marked": "^15.0.12",
     "monaco-editor": "^0.54.0",