Switch "php-ext-install" test to use POSIX instead of Bash (Alpine support)

test/tests/php-ext-install/container.sh

@@ -1,6 +1,5 @@
-#!/bin/bash
-
-set -ueo pipefail
+#!/bin/sh
+set -e
 
 docker-php-ext-install pdo_mysql 2>&1
 php -r 'exit(extension_loaded("pdo_mysql") ? 0 : 1);'

test/tests/php-ext-install/run.sh

@@ -1 +1 @@
-../run-bash-in-container.sh
+../run-sh-in-container.sh