Drop 3.9 support (#164)

Author: paddyroddy

.github/workflows/test.yaml

@@ -26,7 +26,6 @@ jobs:
           - ubuntu-latest
           - windows-latest
         python-version:
-          - "3.9"
           - "3.10"
           - "3.11"
           - "3.12"

pyproject.toml

@@ -41,7 +41,7 @@ optional-dependencies = {dev = [
     "pdoc3",
 ]}
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 urls = {Code = """\
     https://github.com/paddyroddy/python-template\
     """, Documentation = """\
@@ -144,7 +144,6 @@ overrides."tool.ruff.lint.isort.section-order".inline_arrays = false
 legacy_tox_ini = """
     [gh-actions]
     python =
-        3.9: py39
         3.10: py310
         3.11: py311
         3.12: py312