scripts : make the shell scripts cross-platform (#14341)

tools/server/chat-llama2.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 API_URL="${API_URL:-http://127.0.0.1:8080}"
 

tools/server/chat.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 API_URL="${API_URL:-http://127.0.0.1:8080}"
 

tools/server/tests/tests.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # make sure we are in the right directory
 SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )