fcc-unlock: switch bash shell scripts to use sh

This enables the usage with busybox and fixes yocto dependency
issues.

This is related to #483 and the previous commit
91ed72aa29.

data/dispatcher-fcc-unlock/2c7c

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 
 # SPDX-License-Identifier: CC0-1.0
 # 2022 Leah Oswald <mail@leahoswald.de>