chore(deps): bump @ng-select/ng-select in /frontend

Bumps [@ng-select/ng-select](https://github.com/ng-select/ng-select) from 5.0.14 to 5.0.15.
- [Release notes](https://github.com/ng-select/ng-select/releases)
- [Changelog](https://github.com/ng-select/ng-select/blob/master/CHANGELOG.md)
- [Commits](ng-select/ng-select@v5.0.14...v5.0.15)

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

frontend/package.json

@@ -23,7 +23,7 @@
     "@angular/platform-browser": "~11.0.0",
     "@angular/platform-browser-dynamic": "~11.0.0",
     "@angular/router": "~11.0.0",
-    "@ng-select/ng-select": "^5.0.14",
+    "@ng-select/ng-select": "^5.0.15",
     "chart.js": "^2.9.4",
     "core-js": "^3.8.2",
     "ngx-markdown": "^11.0.1",
@@ -40,7 +40,7 @@
     "@angular/language-service": "~11.0.5",
     "@types/jasmine": "~3.6.2",
     "@types/jasminewd2": "~2.0.3",
-    "@types/node": "^14.14.19",
+    "@types/node": "^14.14.20",
     "codelyzer": "^6.0.0",
     "jasmine-core": "~3.6.0",
     "jasmine-spec-reporter": "~6.0.0",