bin: fix get-aws-login on non-nixos

pulumi from nixpkgs applies a LD_LIBRARY_PATH which is propagated to the
credential helper which breaks showing prompts so we just unset it.

.local/bin/get-aws-login

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+unset LD_LIBRARY_PATH
+
 function log {
   if [ -t 1 ]; then
     echo "$@" >&2