Force newer version of maridb than nextcloud/requirements.yaml has

See https://open.greenhost.net/openappstack/openappstack/issues/390

requirements.yaml

@@ -18,6 +18,7 @@ dependencies:
       - key-value-store
       - redis
       - onlyoffice
+      - nextcloud
   - name: postgresql
     version: 7.7.0
     repository: "@stable"
@@ -25,3 +26,13 @@ dependencies:
       - postgresql
       - onlyoffice
       - database
+  # Force newer version of maridb as nextcloud/requirements.yaml have
+  # so we can use k8s 1.16
+  # See https://open.greenhost.net/openappstack/openappstack/issues/390
+  - name: mariadb
+    version: 7.1.0
+    repository: "@stable"
+    tags:
+      - mariadb
+      - nextcloud
+      - database