Update JExcel to version without color picker problem

JExcel 3.9.1 has a bug where the close method is called on a div instead of the color picker object `[1]` should be `[0]`.   Upgrading JExcel solves the issue.

Author: deftdawg

package.json

@@ -19,7 +19,7 @@
     "@angular/platform-browser": "~9.1.0",
     "@angular/platform-browser-dynamic": "~9.1.0",
     "@angular/router": "~9.1.0",
-    "jexcel": "^3.9.1",
+    "jexcel": "^4.2.0",
     "rxjs": "~6.5.4",
     "tslib": "^1.10.0",
     "zone.js": "~0.10.2"