update banner severity (#306)

Author: jwilliams-mongo

snooty.toml

@@ -130,7 +130,7 @@ yaml = ":abbr:`YAML (Yet Another Markup Language)`"
 
 [[banners]]
 targets = ["*"]
-variant = "info"
+variant = "warning"
 value = """\
     **Data Lake is deprecated.** \
     As of September 2024, Data Lake is deprecated and will reach end-of-life. It will be removed on September 30, 2025. If you use Data Lake, you should migrate to alternative solutions before the service is removed. To learn more, see :ref:`data-lake-deprecation-guide`.\