btrfs-progs: tests: use /bin/bash for scripts

Since we use 'source' in scripts, let's use bash everywhere.

Signed-off-by: David Sterba <dsterba@suse.com>

tests/clean-tests.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 # remove all intermediate files from tests
 
 SCRIPT_DIR=$(dirname $(readlink -f $0))

tests/test-console.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 # a shell with test environment set up, logged commands and output
 
 LANG=C