[frontend] Add 'type=rpm-md' to .repo file template

When using Zypper with copr repos, this needs to be added
so that Zypper can properly consume the repository metadata.
Zypper supports repo types of 'rpm-md', 'yast2', and 'plaindir'.
More information is available in zypper(8) under "Repository
Management".

frontend/coprs_frontend/coprs/templates/coprs/copr.repo

@@ -1,6 +1,7 @@
 [{{ copr.repo_id }}]
 name=Copr repo for {{ copr.name }} owned by {{ copr.owner_name }}
 baseurl={{ url | fix_url_https_backend }}
+type=rpm-md
 skip_if_unavailable=True
 gpgcheck={{ config.REPO_GPGCHECK | default("1")}}
 gpgkey={{ pubkey_url | fix_url_https_backend  }}