Bump dhtmlx-gantt from 9.0.15 to 9.1.0 (#168)

Bumps [dhtmlx-gantt](https://github.com/DHTMLX/gantt) from 9.0.15 to 9.1.0.
- [Release notes](https://github.com/DHTMLX/gantt/releases)
- [Changelog](https://github.com/DHTMLX/gantt/blob/master/whatsnew.md)
- [Commits](DHTMLX/gantt@v9.0.15...v9.1.0)

---
updated-dependencies:
- dependency-name: dhtmlx-gantt
  dependency-version: 9.1.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -4,7 +4,7 @@
   "private": true,
   "license": "GPL-2.0-or-later",
   "dependencies": {
-    "dhtmlx-gantt": "^9.0.15"
+    "dhtmlx-gantt": "^9.1.0"
   },
   "scripts": {
     "build": "webpack --config .webpack.config.js",