Drop python 3.8 from CI to simplify dependency hashing (see https://g…

…ithub.com/python-jsonschema/jsonschema/blob/e0f9c69a8b8299b2eba750ee5ac9340f365f8a39/pyproject.toml\#L46C1-L49)

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.9", "3.10", "3.11"]
 
     steps:
       - uses: actions/checkout@v2