Simplify the test GitHub Actions workflow (#384)

Don't need to check the latest dependency versions on the oldest Python.
Just check oldest versions with oldest Python and newest with newest
Python. Otherwise we waste too much compute running tests.

.github/workflows/test.yml

@@ -17,10 +17,6 @@ on:
   release:
     types:
       - published
-  schedule:
-    # Run every Monday at 12:00 UTC
-    # * is a special character in YAML so you have to quote this string
-    - cron: "00 12 * * 1"
 
 # Use bash by default in all jobs
 defaults:
@@ -43,13 +39,17 @@ jobs:
           - ubuntu
           - macos
           - windows
-        python:
-          - "3.7"
-          - "3.11"
         dependencies:
+          - oldest
           - latest
           - optional
-          - oldest
+        include:
+          - dependencies: oldest
+            python: "3.7"
+          - dependencies: latest
+            python: "3.11"
+          - dependencies: optional
+            python: "3.11"
     env:
       REQUIREMENTS: env/requirements-build.txt env/requirements-test.txt
       # Used to tag codecov submissions