Use ubuntu-latest in publish workflow

Ubuntu 20.04 is being retired from GitHub (actions/runner-images#11101).

Definitely churn we shouldn't need to think about (unless it breaks),
so just using latest all the time instead.

Author: BryceStevenWilley

.github/workflows/publish.yml

@@ -5,7 +5,7 @@ on: push
 jobs:
   build-n-publish:
     name: Build and publish Python 🐍 distributions 📦 to PyPI
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
     - uses: SuffolkLITLab/ALActions/publish@main
       with: