Revert "Use #!/bin/bash instead of #!/bin/sh"

This reverts commit 594f972666.

We have not received a reply for the relicensing to GPL-3.0-or-later
from its author @drizzt, which is why we are removing this commit.

lddd.in

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 #
 # lddd - find broken library links on your machine
 #