Bump sortablejs from 1.15.3 to 1.15.6

Bumps [sortablejs](https://github.com/SortableJS/Sortable) from 1.15.3 to 1.15.6.
- [Release notes](https://github.com/SortableJS/Sortable/releases)
- [Commits](https://github.com/SortableJS/Sortable/compare/1.15.3...1.15.6)

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

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

package.json

@@ -117,7 +117,7 @@
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.0",
     "sanitize-html": "^2.13.1",
-    "sortablejs": "1.15.3",
+    "sortablejs": "1.15.6",
     "uuid": "^8.3.2",
     "zone.js": "~0.13.3"
   },

yarn.lock

@@ -10650,10 +10650,10 @@ socks@^2.6.2:
     ip "^2.0.0"
     smart-buffer "^4.2.0"
 
-sortablejs@1.15.3:
-  version "1.15.3"
-  resolved "https://registry.yarnpkg.com/sortablejs/-/sortablejs-1.15.3.tgz#033668db5ebfb11167d1249ab88e748f27959e29"
-  integrity sha512-zdK3/kwwAK1cJgy1rwl1YtNTbRmc8qW/+vgXf75A7NHag5of4pyI6uK86ktmQETyWRH7IGaE73uZOOBcGxgqZg==
+sortablejs@1.15.6:
+  version "1.15.6"
+  resolved "https://registry.yarnpkg.com/sortablejs/-/sortablejs-1.15.6.tgz#ff93699493f5b8ab8d828f933227b4988df1d393"
+  integrity sha512-aNfiuwMEpfBM/CN6LY0ibyhxPfPbyFeBTYJKCvzkJ2GkUpazIt3H+QIPAMHwqQ7tMKaHz1Qj+rJJCqljnf4p3A==
 
 source-list-map@^2.0.0:
   version "2.0.1"