Raise ValueError instead of Exception.

src/tiledb/cloud/client.py

@@ -102,7 +102,7 @@ def login_to_region(region: Region, **kwargs):
     :return:
     """
     if not Region.contains(region):
-        raise Exception("Cloud region is invalid")
+        raise ValueError(f"region {region} is invalid")
     login(**dict(kwargs, host=region.value))