fix: set version only and let pg_wrapper figure our the relevant cluster

Signed-off-by: F.N. Claessen <felix@seita.nl>

flexmeasures/cli/db_ops.py

@@ -161,7 +161,7 @@ def pg_cluster_arg_from_version(pg_version: str | None) -> str:
     More info (e.g. on the format) at https://manpages.ubuntu.com/manpages/trusty/man1/pg_wrapper.1.html
     """
     if pg_version:
-        return f"--cluster {pg_version}/main"
+        return f"--version {pg_version}"
     return ""