ci: add Rails 8.1.0.rc1 to test matrix

Author: seuros

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
-    
+
     services:
       postgres:
         image: postgres:17-alpine
@@ -26,7 +26,7 @@ jobs:
           --health-interval 10s
           --health-timeout 5s
           --health-retries 5
-          
+
       mysql:
         image: mysql:8
         ports:
@@ -47,6 +47,7 @@ jobs:
           - '3.4'
         rails:
           - '8.0'
+          - '8.1.0.rc1'
 
     steps:
       - name: Checkout