Mark 3.13 as unsupported (#98)

* Update readme with red python 3.13 badge, update pyproject as 3.13 unsupported.

* update checkout versions

.github/workflows/black.yml

@@ -6,5 +6,5 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: psf/black@stable

.github/workflows/tests.yml

@@ -25,7 +25,7 @@ jobs:
         python-version: ["3.8", "3.9", "3.10", "3.11"]
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Set up Python 3.10
       uses: actions/setup-python@v4
       with:

README.md

@@ -1,6 +1,8 @@
 # adtl – another data transformation language
 
-[![](https://img.shields.io/badge/python-3.8+-blue.svg)](https://www.python.org/downloads/)
+[![Python 3.8+](https://img.shields.io/badge/python-3.8+-blue.svg)](https://www.python.org/downloads/)
+[![Python 3.13](https://img.shields.io/badge/python-3.13-red.svg)](https://www.python.org/downloads/release/python-3130/)
+
 [![tests](https://github.com/globaldothealth/adtl/actions/workflows/tests.yml/badge.svg)](https://github.com/globaldothealth/adtl/actions/workflows/tests.yml)
 [![codecov](https://codecov.io/gh/globaldothealth/adtl/branch/main/graph/badge.svg?token=QTD7HRR3TO)](https://codecov.io/gh/globaldothealth/adtl)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)

pyproject.toml

@@ -14,7 +14,7 @@ authors = [
   {name = "Pip Liggins", email = "philippa.liggins@dtc.ox.ac.uk"}
 ]
 license = {file = "LICENSE"}
-requires-python = ">=3.8"
+requires-python = ">=3.8, <3.13" # 3.13 not supported by pint, so temporary upper bound
 readme = "README.md"
 classifiers = ["License :: OSI Approved :: MIT License"]
 dependencies = [