Drop Python 3.9 support

I'm removing Python 3.9 from the tests as it's now really quite old.

Author: rwb27

.github/workflows/test.yml

@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ["3.9", "3.10", "3.11", "3.12"]
+        python: ["3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v3
@@ -69,7 +69,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ["3.9", "3.10", "3.11", "3.12"]
+        python: ["3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v3

pyproject.toml

@@ -6,7 +6,7 @@ authors = [
 ]
 description = "A test implementation of LabThings using FastAPI"
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 classifiers = [
   "Programming Language :: Python :: 3",
   "License :: OSI Approved :: MIT License",