Bump tinymce from 4.9.2 to 4.9.7 in /src/Umbraco.Web.UI.Client

Bumps [tinymce](https://github.com/tinymce/tinymce-dist) from 4.9.2 to 4.9.7.
- [Release notes](https://github.com/tinymce/tinymce-dist/releases)
- [Changelog](https://github.com/tinymce/tinymce-dist/blob/4.9.7/changelog.txt)
- [Commits](https://github.com/tinymce/tinymce-dist/compare/4.9.2...4.9.7)

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

src/Umbraco.Web.UI.Client/package.json

@@ -42,7 +42,7 @@
     "npm": "6.13.6",
     "signalr": "2.4.0",
     "spectrum-colorpicker": "1.8.0",
-    "tinymce": "4.9.2",
+    "tinymce": "4.9.7",
     "typeahead.js": "0.11.1",
     "underscore": "1.9.1"
   },