Drop Python 3.9 support (#272)

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

URL: #272

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

@@ -34,7 +34,7 @@ dependencies:
 - pytest-asyncio
 - pytest-rerunfailures
 - pytest==7.*
-- python>=3.9,<3.12
+- python>=3.10,<3.12
 - rapids-build-backend>=0.3.0,<0.4.0.dev0
 - rapids-dask-dependency==24.10.*,>=0.0.0a0
 - rmm==24.10.*,>=0.0.0a0

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

@@ -34,7 +34,7 @@ dependencies:
 - pytest-asyncio
 - pytest-rerunfailures
 - pytest==7.*
-- python>=3.9,<3.12
+- python>=3.10,<3.12
 - rapids-build-backend>=0.3.0,<0.4.0.dev0
 - rapids-dask-dependency==24.10.*,>=0.0.0a0
 - rmm==24.10.*,>=0.0.0a0

conda/recipes/ucxx/conda_build_config.yaml

@@ -20,7 +20,6 @@ cmake:
   - ">=3.26.4"
 
 python:
-  - 3.9
   - 3.10
   - 3.11
 

dependencies.yaml

@@ -263,10 +263,6 @@ dependencies:
     specific:
       - output_types: conda
         matrices:
-          - matrix:
-              py: "3.9"
-            packages:
-              - python=3.9
           - matrix:
               py: "3.10"
             packages:
@@ -277,7 +273,7 @@ dependencies:
               - python=3.11
           - matrix:
             packages:
-              - python>=3.9,<3.12
+              - python>=3.10,<3.12
   run_python_ucxx:
     common:
       - output_types: [conda, requirements, pyproject]

python/distributed-ucxx/pyproject.toml

@@ -14,7 +14,7 @@ authors = [
     { name = "NVIDIA Corporation" },
 ]
 license = { text = "BSD-3-Clause" }
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 dependencies = [
     "numba>=0.57.1",
     "rapids-dask-dependency==24.10.*,>=0.0.0a0",
@@ -24,7 +24,6 @@ classifiers = [
     "Intended Audience :: Developers",
     "License :: OSI Approved :: Apache Software License",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
 ]

python/ucxx/pyproject.toml

@@ -17,7 +17,7 @@ authors = [
     { name = "NVIDIA Corporation" },
 ]
 license = { text = "BSD-3-Clause" }
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 dependencies = [
     "libucxx==0.40.*,>=0.0.0a0",
     "numpy>=1.23,<3.0a0",