chore: use node20 for runtime to fix tests (no-release) (#58)

Node14 no longer supported, tests fail because of this

examples/complete/fixtures.us-east-2.tfvars

@@ -5,5 +5,5 @@ stage       = "test"
 
 function_name          = "example-complete"
 handler                = "handler.handler"
-runtime                = "nodejs14.x"
+runtime                = "nodejs20.x"
 ephemeral_storage_size = 1024