build(deps): lock min Python version to 3.7.9

Github Actions for windows uses Python 3.7.9 not 3.7.16. This wasn't
picked up in the PR that introduced the original lock because of
dependency caching. See:

https://github.com/openlawlibrary/pygls/actions/runs/5702563535/job/15454396739#step:6:12

pyproject.toml

@@ -13,7 +13,7 @@ license = "Apache 2.0"
 readme = "README.md"
 
 [tool.poetry.dependencies]
-python = ">=3.7.16,<4"
+python = ">=3.7.9,<4"
 lsprotocol = "2023.0.0a2"
 typeguard = "^3.0.0"
 websockets = {version = "^11.0.3", optional = true}