do not force unwrap

Revert a change from #d2bd7f1aae1fc9455b208567ba5d85e42463c82c that caused the plugin to crash

Author: sebsto

Plugins/AWSLambdaPackager/PluginUtils.swift

@@ -32,7 +32,7 @@ struct Utils {
 
         let fd = dup(1)
         let stdout = fdopen(fd, "rw")
-        defer { fclose(stdout!) }
+        defer { fclose(stdout) }
 
         // We need to use an unsafe transfer here to get the fd into our Sendable closure.
         // This transfer is fine, because we write to the variable from a single SerialDispatchQueue here.