dev: increment minimum python version to 3.9

pyproject.toml

@@ -17,10 +17,8 @@ channels = ["conda-forge"]
 platforms = ["linux-64"]
 
 [tool.pixi.dependencies]
-python = ">=3.8"
+python = ">=3.9"
 
-[tool.pixi.feature.py308.dependencies]
-python = "3.8.*"
 [tool.pixi.feature.py309.dependencies]
 python = "3.9.*"
 [tool.pixi.feature.py310.dependencies]
@@ -60,7 +58,6 @@ rockervsc = "rockervsc.rockervsc:run_rockervsc"
 # Environments
 [tool.pixi.environments]
 default = {features = ["test"], solve-group = "default" }
-py308 = ["py308","test"]
 py309 = ["py309","test"]
 py310 = ["py310","test"]
 py311 = ["py311","test"]