Bump prosemirror-model from 1.14.3 to 1.15.0

Bumps [prosemirror-model](https://github.com/prosemirror/prosemirror-model) from 1.14.3 to 1.15.0.
- [Release notes](https://github.com/prosemirror/prosemirror-model/releases)
- [Changelog](https://github.com/ProseMirror/prosemirror-model/blob/master/CHANGELOG.md)
- [Commits](ProseMirror/prosemirror-model@1.14.3...1.15.0)

---
updated-dependencies:
- dependency-name: prosemirror-model
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

package.json

@@ -44,7 +44,7 @@
 		"prosemirror-collab": "^1.2.2",
 		"prosemirror-inputrules": "^1.1.3",
 		"prosemirror-markdown": "^1.6.0",
-		"prosemirror-model": "^1.14.1",
+		"prosemirror-model": "^1.15.0",
 		"prosemirror-schema-list": "^1.1.6",
 		"prosemirror-state": "^1.3.4",
 		"prosemirror-transform": "^1.3.3",