Bump min python to 3.9

Author: sjmonson

pyproject.toml

@@ -20,7 +20,7 @@ name = "guidellm"
 version = "0.1.0"
 description = "Guidance platform for deploying and managing large language models."
 readme = { file = "README.md", content-type = "text/markdown" }
-requires-python = ">=3.8.0,<4.0"
+requires-python = ">=3.9.0,<4.0"
 license = { file = "LICENSE" }
 authors = [ { name = "Neuralmagic, Inc." } ]
 urls = { homepage = "https://github.com/neuralmagic/guidellm" }