ci: pin setuptools<81 to retain pkg_resources for pyewts build

setuptools 81 (July 2025) removed the implicit bundling of
pkg_resources, which pyewts 0.2.0's setup.py imports at build time.
Upgrading setuptools on CI moved the runner from a working 79.x
to a 82.x that breaks the install. Pinning <81 keeps the build
working without touching runtime dependencies or requirements.txt.

Author: evanyerburgh

.github/workflows/test.yml

@@ -26,7 +26,7 @@ jobs:
 
     - name: Install dependencies
       run: |
-        python -m pip install --upgrade pip setuptools wheel
+        python -m pip install --upgrade pip "setuptools<81" wheel
         pip install -r requirements.txt --no-build-isolation
 
     - name: Run test