bash: Use /usr/bin/env to make it distro agnostic

Not all distributions have bash at /bin/bash, for example NixOS does
not. But `/usr/bin/env bash` works on every distribution because its
finds bash from the PATH.

Signed-off-by: Daniel Schaefer <dhs@frame.work>

Author: JohnAZoidberg

test-case/check-8bit-play-rec.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 ##
 ## Case Name: check-8bit-play-rec

test-case/check-alsa-conformance.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Copyright(c) 2025 Intel Corporation.
 # SPDX-License-Identifier: BSD-3-Clause

test-case/check-alsabat.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 ##
 ## Case Name: check alsabat

test-case/check-audio-equalizer.sh

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

test-case/check-capture.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 ##
 ## Case Name: check-capture

test-case/check-float-play-rec.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 ##
 ## Case Name: check-float-play-rec

test-case/check-fw-echo-reference.sh

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

test-case/check-ipc-flood.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 ##
 ## Case Name: ipc flood

test-case/check-keyword-detection.sh

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

test-case/check-kmod-load-unload-after-playback.sh

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