Use recent Spring Framework versions on CI

Author: snicoll

.github/workflows/ci.yml

@@ -18,9 +18,9 @@ jobs:
             toolchain: false
         spring:
           - generation: 6.1.x
-            version: 6.1.14
+            version: 6.1.21
           - generation: 6.2.x
-            version: 6.2.0-SNAPSHOT
+            version: 6.2.12
     steps:
       - name: Check Out Code
         uses: actions/checkout@v4