Specify python patch version in circleci conf.

.circleci/config.yml

@@ -6,13 +6,13 @@ version: 2.1
 executors:
   python:
     docker:
-      - image: circleci/python:3.8
+      - image: circleci/python:3.8.9
   node:
     docker:
       - image: circleci/node:12
   with-database:
     docker:
-      - image: circleci/python:3.8
+      - image: circleci/python:3.8.9
         environment:
           DATABASE_URL: postgresql://hypha:hypha@localhost/hypha?sslmode=disable
           DJANGO_SETTINGS_MODULE: hypha.settings.test