QA: Replace shebang with env-variant

This is to provide a compatibility with nix such as GNU Guix to use the
project painlessly without the need of deploying a sandboxed FHS
environment.

Signed-off-by: Jacob Hrbek <kreyren@rixotstudio.cz>

src/hooks/hook-ethernet-dhcp.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e
 

src/hooks/hook-parabola-buildbox.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e
 

src/pvm-common.sh.inc

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 ###############################################################################
 #     parabola-vmbootstrap -- create and start parabola virtual machines      #
 #                                                                             #

src/pvm2tarball.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 ###############################################################################
 #     parabola-vmbootstrap -- create and start parabola virtual machines      #
 #                                                                             #

src/pvmboot.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 ###############################################################################
 #     parabola-vmbootstrap -- create and start parabola virtual machines      #
 #                                                                             #

src/pvmbootstrap.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 ###############################################################################
 #     parabola-vmbootstrap -- create and start parabola virtual machines      #
 #                                                                             #
@@ -317,7 +317,7 @@ pvm_bootstrap() # assumes: $arch $imagefile $loopdev $workdir , traps: INT TERM
   # create a master hook script
   msg2 "hooks.sh:"
   sudo tee "$workdir"/root/hooks.sh << EOF
-#!/bin/bash
+#!/usr/bin/env bash
 echo "[hooks.sh] boot successful - configuring ...."
 
 # generate the locale