Use more general image tags, use bullseye

Author: jhrcek

.circleci/config.yml

@@ -60,14 +60,14 @@ version: 2
 jobs:
   stackage-lts22:
     docker:
-      - image: haskell:9.6.6-slim-buster
+      - image: haskell:9.6-slim-bullseye
     environment:
       - STACK_FILE: "stack-lts22.yaml"
     <<: *defaults
 
   stackage-nightly:
     docker:
-      - image: haskell:9.8.4-slim-buster
+      - image: haskell:9.8-slim-bullseye
     environment:
       - STACK_FILE: "stack.yaml"
     <<: *defaults