Update dependency django-storages to v1.13

Author: renovate[bot]

requirements-container.txt

@@ -1,5 +1,5 @@
 django-auth-ldap==4.1.0
-django-storages[azure,boto3,dropbox,google,libcloud,sftp]==1.12.3
+django-storages[azure,boto3,dropbox,google,libcloud,sftp]==1.13
 napalm==4.0.0
 psycopg2==2.9.3
 social-auth-core[openidconnect]==4.3.0