Improvements to tox.ini setup

- Correctly call the new Cy2026 impl, caveats, and examples tests
- Ensure running tox locally will be able to find python 3.7. This will
also get applied to the github actions.

Author: MHendricks

.github/actions/setup-tox/action.yml

@@ -63,9 +63,7 @@ runs:
 
     - name: Install dependencies
       shell: bash
-      # NOTE: The virtualenv and tox requirements support finding python 3.7,
-      # if we drop support for python 3.7 the reqs can be simplified and updated
       run: |
         python --version
         python -m pip install --upgrade pip
-        python -m pip install "tox<=4.23.2" "virtualenv<=20.26.6"
+        python -m pip install tox

tox.ini

@@ -44,7 +44,7 @@ envlist =
     # Cy2024, Cy2025
     test-py311-{PySide,PyQt}6.5-{impl,caveats,examples}
     # Cy2026
-    test-py313-{PySide,PyQt}6.8
+    test-py313-{PySide,PyQt}6.8-{impl,caveats,examples}
     # Test newer versions of python/Qt than VFX Reference Platform has chosen
     test-py{312}-{PySide,PyQt}{6.8}-{impl,caveats,examples}
     test-py{314}-{PySide,PyQt}{6.9}-{impl,caveats,examples}
@@ -55,6 +55,11 @@ envlist =
     mypy
 
 skip_missing_interpreters = True
+requires =
+    # NOTE: The virtualenv and tox requirements support finding python 3.7,
+    # if we drop support for python 3.7 the reqs can be simplified and updated.
+    tox<=4.23.2
+    virtualenv<=20.26.6
 
 [testenv]
 # These are used by all other testenv definitions unless overridden