Enabled activerecord next testing

Author: wollistik

.github/workflows/ci.yml

@@ -36,12 +36,12 @@ jobs:
             gemfile: ar_61
           - ruby-version: '3.0'
             gemfile: ar_52
-#          - ruby-version: '2.6'
-#            gemfile: ar_next
+          - ruby-version: '2.6'
+            gemfile: ar_next
           - ruby-version: '2.6'
             gemfile: ar_70
-#          - ruby-version: '2.5'
-#            gemfile: ar_next
+          - ruby-version: '2.5'
+            gemfile: ar_next
           - ruby-version: '2.5'
             gemfile: ar_70
     env: # $BUNDLE_GEMFILE must be set at the job level, so it is set for all steps