Bump chart.js from 2.7.2 to 2.9.4

Bumps [chart.js](https://github.com/chartjs/Chart.js) from 2.7.2 to 2.9.4.
- [Release notes](https://github.com/chartjs/Chart.js/releases)
- [Commits](chartjs/Chart.js@v2.7.2...v2.9.4)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -4,7 +4,7 @@
   "private": true,
   "dependencies": {
     "body-parser": "1.18.2",
-    "chart.js": "2.7.2",
+    "chart.js": "2.9.4",
     "cors": "2.8.4",
     "d3": "5.0.0",
     "express": "4.17.3",