Set minimum supported version to Python 3.10+ (#76)

* Set minimum supported version to Python 3.10+

Following [SPEC 0](https://scientific-python.org/specs/spec-0000/) policy where Python 3.9 should be dropped in 2024 quarter 4.

* Bump actions/checkout to v4, actions/setup-python to v5

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 4 to 5.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v4...v5)

* Set pyupgrade pre-commit hook to use --py310-plus

Author: weiji14

.github/workflows/pypi-release.yaml

@@ -22,13 +22,15 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository == 'xarray-contrib/cupy-xarray'
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: actions/setup-python@v4
-        name: Install Python
+          persist-credentials: false
+
+      - name: Install Python
+        uses: actions/setup-python@v5
         with:
-          python-version: 3.8
+          python-version: "3.10"
 
       - name: Install dependencies
         run: |

.pre-commit-config.yaml

@@ -25,7 +25,7 @@ repos:
     hooks:
       - id: pyupgrade
         args:
-          - "--py38-plus"
+          - "--py310-plus"
 
   - repo: https://github.com/keewis/blackdoc
     rev: v0.3.9

pyproject.toml

@@ -8,7 +8,7 @@ description = "Interface for using cupy in xarray, providing convenience accesso
 authors = [{name = "cupy-xarray developers"}]
 license = {text = "Apache License"}
 readme = "README.md"
-requires-python = ">=3.8"
+requires-python = ">=3.10"
 classifiers = [
     "Programming Language :: Python :: 3",
     "Operating System :: OS Independent",