update python versions

Author: LiamConnors

.circleci/config.yml

@@ -3,7 +3,7 @@ version: 2
 jobs:
     python-3.8: &test-template
         docker:
-            - image: circleci/python:3.8-stretch-node-browsers
+            - image: cimg/python:3.8.20-browsers
               auth:
                 username: dashautomation
                 password: $DASH_PAT_DOCKERHUB
@@ -47,7 +47,7 @@ jobs:
 
     python-3.12-install-test:
         docker:
-            - image: circleci/python:3.12-stretch-node-browsers
+            - image: cimg/python:3.12.7-browsers
               auth:
                 username: dashautomation
                 password: $DASH_PAT_DOCKERHUB