maintainers/scripts: Use Bash shebang line for files with bashisms

maintainers/scripts/debian-patches.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
 # Download patches from debian project
 # Usage $0 debian-patches.txt debian-patches.nix

maintainers/scripts/eval-release.sh

@@ -1,4 +1,4 @@
-#! /bin/sh
+#!/usr/bin/env bash
 
 if [[ -z "$VERBOSE" ]]; then
   echo "You may set VERBOSE=1 to see debug output or to any other non-empty string to make this script completely silent"

maintainers/scripts/update-channel-branches.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 set -e
 
 : ${NIXOS_CHANNELS:=https://nixos.org/channels/}