Update dependency vega to v5.23.0 [SECURITY]

Author: renovate[bot]

package.json

@@ -30,7 +30,7 @@
     "react-router-dom": "4.3.1",
     "react-scripts": "2.0.0-next.3e165448",
     "react-select": "2.0.0",
-    "vega": "5.6.0",
+    "vega": "5.23.0",
     "vega-lite": "3.4.0",
     "vega-tooltip": "0.13.0"
   },