fix(CI): pin deno version

Author: juliamertz

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Setup Deno
         uses: denoland/setup-deno@v2
         with:
-          deno-version: v2.x
+          deno-version: v2.6.4
 
       - name: Check formatting
         run: deno fmt --check