Bump summernote from 0.8.18 to 0.8.20

Bumps [summernote](https://github.com/summernote/summernote) from 0.8.18 to 0.8.20.
- [Release notes](https://github.com/summernote/summernote/releases)
- [Changelog](https://github.com/summernote/summernote/blob/v0.8.20/CHANGES.md)
- [Commits](summernote/summernote@v0.8.18...v0.8.20)

---
updated-dependencies:
- dependency-name: summernote
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -36,7 +36,7 @@
     "ngx-markdown": "^12.0.1",
     "ngx-summernote": "^0.8.7",
     "rxjs": "^6.6.0",
-    "summernote": "^0.8.18",
+    "summernote": "^0.8.20",
     "tslib": "^2.3.1",
     "uuid": "^8.3.2",
     "zone.js": "~0.11.4"