trust: zero is a valid number of TSAs for now

Signed-off-by: Jussi Kukkonen <jkukkonen@google.com>

Author: jku

sigstore/_internal/trust.py

@@ -424,8 +424,6 @@ def get_tsas(self) -> list[TimestampAuthorityClient]:
         """
         Returns timestamp authority API end points.
         """
-        if not self._tsas:
-            raise Error("No valid Rekor transparency log found in signing config")
         return [TimestampAuthorityClient(s.url) for s in self._tsas]