fix(ci): replace Deno 2.3.0 with 2.1.4 to avoid fs.close() bug

Deno 2.3.0 has a known bug where fs.close() requires a callback even
though it should be optional according to Node.js documentation. This
causes test failures with "TypeError: callback is not a function" errors.

Using Deno 2.1.4 as the minimum tested version instead, while keeping
2.x for testing with the latest version.

See: denoland/deno#30718

Author: lambdalisue

.github/workflows/test.yml

@@ -69,7 +69,7 @@ jobs:
           - macos-latest
           - ubuntu-latest
         deno_version:
-          - "2.3.0"
+          - "2.1.4"  # Use 2.1.4 instead of 2.3.0 which has fs.close() bug
           - "2.x"
         host_version:
           - vim: "v9.1.1646"