updated timestamp conversion to use Luxon and adrs-adr012 guideline, added luxon as dependency

Signed-off-by: Jeremy Guarini <jguarini@paloaltonetworks.com>

plugins/code-coverage/package.json

@@ -33,6 +33,7 @@
     "@material-ui/lab": "4.0.0-alpha.57",
     "@material-ui/styles": "^4.11.0",
     "highlight.js": "^10.6.0",
+    "luxon": "^2.1.0",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",
     "react-router": "6.0.0-beta.0",

plugins/code-coverage/src/components/CoverageHistoryChart/CoverageHistoryChart.tsx

@@ -46,6 +46,8 @@ import { codeCoverageApiRef } from '../../api';
 import { Progress, ResponseErrorPanel } from '@backstage/core-components';
 import { useApi } from '@backstage/core-plugin-api';
 
+import { DateTime } from 'luxon';
+
 type Coverage = 'line' | 'branch';
 
 const useStyles = makeStyles<BackstageTheme>(theme => ({
@@ -71,7 +73,9 @@ const getTrendIcon = (trend: number, classes: ClassNameMap) => {
 
 // convert timestamp to human friendly form
 function formatDateToHuman(timeStamp: string | number) {
-  return new Date(timeStamp).toUTCString();
+  return DateTime.fromMillis(Number(timeStamp)).toLocaleString(
+    DateTime.DATETIME_MED,
+  );
 }
 
 export const CoverageHistoryChart = () => {