config: replace CI legacy images with 'next-gen'

.circleci/config.yml

@@ -1,17 +1,19 @@
 version: 2 # use CircleCI 2.0
+# NOTE: images have been migrated to 'next-gen'
+# see: https://discuss.circleci.com/t/legacy-convenience-image-deprecation/41034
 jobs: # a collection of steps
   build: # runs not using Workflows must have a `build` job as entry point
     parallelism: 3 # run three instances of this job in parallel
     docker: # run the steps with Docker
-      - image: circleci/ruby:2.7.8-node-browsers # ...with this image as the primary container; this is where all `steps` will run
+      - image: cimg/ruby:2.7.8-browsers # ...with this image as the primary container; this is where all `steps` will run
         environment: # environment variables for primary container
           BUNDLE_JOBS: 3
           BUNDLE_RETRY: 3
           BUNDLE_PATH: vendor/bundle
           PGHOST: 127.0.0.1
           PGUSER: postgres
           RAILS_ENV: test
-      - image: circleci/postgres:9.5-alpine # database image
+      - image: cimg/postgres:14.12 # database image
     steps: # a collection of executable commands
       - checkout # special step to check out source code to working directory