Merge pull request #9634 from mpickering/wip/bin-bash

testsuite: Fix hardcoded /bin/bash in custom-cc wrapper

Author: mergify[bot]

cabal-testsuite/PackageTests/CCompilerOverride/custom-cc

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 if which cc >/dev/null 2>&1; then
     cc -DNOERROR6 "${@}"