fix: update shebang to env bash and add strict mode for safer script execution in xgettext.sh

luci-app-podkop/msgmerge.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 set -euo pipefail
 
 PODIR="po"

luci-app-podkop/xgettext.sh

@@ -1,4 +1,5 @@
-#!/bin/bash
+#!/usr/bin/env bash
+set -euo pipefail
 
 SRC_DIR="htdocs/luci-static/resources/view/podkop"
 OUT_POT="po/templates/podkop.pot"