Portability improvements in scripts

* Not all systems have GNU sed, so don't assume `sed -i` works
* Not all systems have /bin/bash, so use `env` to find bash

bundle_migration_plugin.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Copyright (c) 2021-2023 Leseratte10
 # This file is part of the ACSM Input Plugin by Leseratte10