Really disabled building for epel8

I tried to disable this in a9639e680b, but
it was still built.  I believe el8 is the correct platform name to
filter out to prevent stream expansion from building in epel8.  See
rhbz#2042653 for more information.

nextcloud.yaml

@@ -0,0 +1,49 @@
+document: modulemd
+version: 2
+data:
+    summary: A private file sync and share server - version 22.0.x
+    description: >-
+        Nextcloud gives you universal access to your files through a
+        web interface or WebDAV. It also provides a platform to easily
+        view & sync your contacts, calendars and bookmarks across all
+        your devices and enables basic editing right on the web.
+        Nextcloud is extendable via a simple but powerful API for
+        applications and plugins.
+
+    license:
+        module:
+            - MIT
+    dependencies:
+      - buildrequires:
+            platform: [-eln, -el8]
+        requires:
+            platform: [-eln, -el8]
+    references:
+        documentation: https://docs.nextcloud.com/server/latest/admin_manual/
+        tracker: https://github.com/nextcloud/server/issues
+    api:
+        rpms:
+            - nextcloud
+            - nextcloud-httpd
+            - nextcloud-nginx
+            - nextcloud-mysql
+            - nextcloud-postgresql
+            - nextcloud-sqlite
+    profiles:
+        default:
+            description: A standard installation using HTTPD and MySQL.
+            rpms:
+                - nextcloud
+                - nextcloud-httpd
+                - nextcloud-mysql
+        testing:
+            description: A minimal installation for testing purposes
+            rpms:
+                - nextcloud
+                - nextcloud-httpd
+                - nextcloud-sqlite
+    components:
+        rpms:
+            nextcloud:
+                ref: nextcloud-22
+                rationale: Provides the functionality