Make next release 21 only

Signed-off-by: Julius Härtl <jus@bitgrid.net>

appinfo/info.xml

@@ -6,7 +6,7 @@
 	<description><![CDATA[This application can connect to a Collabora Online (or other) server (WOPI-like Client). Nextcloud is the WOPI Host. Please read the documentation to learn more about that.
 
 You can also edit your documents off-line with the Collabora Office app from the **[Android](https://play.google.com/store/apps/details?id=com.collabora.libreoffice)** and **[iOS](https://apps.apple.com/us/app/collabora-office/id1440482071)** store.]]></description>
-	<version>3.7.14</version>
+	<version>4.0.0-beta1</version>
 	<licence>agpl</licence>
 	<author>Collabora Productivity based on work of Frank Karlitschek, Victor Dubiniuk</author>
 	<types>
@@ -29,7 +29,7 @@ You can also edit your documents off-line with the Collabora Office app from the
 	<screenshot>https://www.collaboraoffice.com/downloads/nextcloud/richdocuments/collabora-online-screenshot-4.png</screenshot>
 	<screenshot>https://www.collaboraoffice.com/downloads/nextcloud/richdocuments/collabora-online-screenshot-5.png</screenshot>
 	<dependencies>
-		<nextcloud min-version="15" max-version="20" />
+		<nextcloud min-version="21" max-version="21" />
 	</dependencies>
 	<background-jobs>
 		<job>OCA\Richdocuments\Backgroundjobs\ObtainCapabilities</job>