Update crystal version matrix in ci.yml

.github/workflows/ci.yml

@@ -38,11 +38,10 @@ jobs:
       matrix:
         stable: [true]
         crystal:
-          - 1.4.1
-          - 1.5.1
           - 1.6.2
           - 1.7.3
           - 1.8.2
+          - 1.9.2
         include:
           - crystal: nightly
             stable: false