Enhancement: Bump Web to 11.3.4

- Bugfix [owncloud/web#12598](https://github.com/owncloud/web/pull/12598): Add src attribute to external app iframe
- Bugfix [owncloud/web#12474](https://github.com/owncloud/web/pull/12474): Add tag characters limit

https://github.com/owncloud/web/pull/12605
https://github.com/owncloud/web/releases/tag/v11.3.4
