install with go install since snap does not support s390x

Author: carlcsaposs-canonical

spread.yaml

@@ -120,7 +120,7 @@ prepare: |
   snap refresh --hold
   chown -R root:root "$SPREAD_PATH"
   cd "$SPREAD_PATH"
-  snap install --classic concierge
+  go install github.com/canonical/concierge@latest
 
   # Install charmcraft & pipx on lxd-vm backend and install pipx on IS-hosted runners
   concierge prepare --trace