Drop Python 3.9 support (#209)

Contributes to rapidsai/build-planning#88

Finishes the work of dropping Python 3.9 support.

This project stopped building / testing against Python 3.9 as of rapidsai/shared-workflows#235.
This PR updates configuration and docs to reflect that.

## Notes for Reviewers

### How I tested this

Checked that there were no remaining uses like this:

```shell
git grep -E '3\.9'
git grep '39'
git grep 'py39'
```

And similar for variations on Python 3.8 (to catch things that were missed the last time this was done).

Authors:
  - James Lamb (https://github.com/jameslamb)

Approvers:
  - Bradley Dice (https://github.com/bdice)

URL: #209

conda/environments/all_cuda-118_arch-x86_64.yaml

@@ -38,7 +38,7 @@ dependencies:
 - pytest
 - pytest-forked
 - pytest-xdist
-- python>=3.9,<3.12
+- python>=3.10,<3.12
 - pytorch-cuda=11.8
 - pytorch=2.0.0
 - rapids-build-backend>=0.3.0,<0.4.0.dev0

conda/environments/all_cuda-125_arch-x86_64.yaml

@@ -39,7 +39,7 @@ dependencies:
 - pytest
 - pytest-forked
 - pytest-xdist
-- python>=3.9,<3.12
+- python>=3.10,<3.12
 - rapids-build-backend>=0.3.0,<0.4.0.dev0
 - recommonmark
 - scikit-build-core>=0.10.0

dependencies.yaml

@@ -193,10 +193,6 @@ dependencies:
     specific:
       - output_types: conda
         matrices:
-          - matrix:
-              py: "3.9"
-            packages:
-              - python=3.9
           - matrix:
               py: "3.10"
             packages:
@@ -207,7 +203,7 @@ dependencies:
               - python=3.11
           - matrix:
             packages:
-              - python>=3.9,<3.12
+              - python>=3.10,<3.12
   run:
     common:
       - output_types: [conda, requirements]

python/pylibwholegraph/pyproject.toml

@@ -27,15 +27,11 @@ authors = [
     { name = "NVIDIA Corporation" },
 ]
 license = { text = "Apache 2.0" }
-requires-python = ">=3.6"
+requires-python = ">=3.10"
 classifiers = [
     "Intended Audience :: Developers",
     "License :: OSI Approved :: Apache Software License",
     "Programming Language :: Python",
-    "Programming Language :: Python :: 3.6",
-    "Programming Language :: Python :: 3.7",
-    "Programming Language :: Python :: 3.8",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
 ]