DELIVERY-225 fix file not found

Following [DELIVERY-213](https://retool.atlassian.net/browse/DELIVERY-213) we didn't fixed the error

The argument passed to `syscall.Exec` (`os.Args[0]`) suppose
relative binary will be found/resolved properly

It succeeded with `./releases/aww-darwin-amd64` and `/usr/local/bin/aww`
but failed with path call `aww`

Using absolute destination enforce the absolute resolution and hence resolves the error for further releases

s3update.go

@@ -159,7 +159,7 @@ func runAutoUpdate(u Updater) error {
 		fmt.Printf("s3update: updated with success to version %d\nRestarting application\n", remoteVersion)
 
 		// The update completed, we can now restart the application without requiring any user action.
-		if err := syscall.Exec(os.Args[0], os.Args, os.Environ()); err != nil {
+		if err := syscall.Exec(dest, os.Args, os.Environ()); err != nil {
 			return err
 		}