Update tests.yml

Correct version for Aiken. Since 1.25 there is a bug in aiken. We've opened a issue aiken-lang/aiken#921

Author: jmagan

.github/workflows/tests.yml

@@ -13,7 +13,7 @@ jobs:
 
       - uses: aiken-lang/[email protected]
         with:
-          version: v1
+          version: v1.0.24-alpha
 
       - run: aiken fmt --check
       - run: aiken check -D