Added PGPASSWORD environment variable to Postgres restore command.

[spleenboy]

Using the Postgres driver, attempt to restore using Craft::$app->getDb()->restore($backupPath) fails with the following error. This pull request adds the password to the environment using the same method as the getDefaultBackupCommand method.

craft\errors\ShellCommandException: The shell command "psql --dbname=craft --host=postgres --port=5432 --username=craft_user --no-password < "storage/backups/backup.sql"" failed with exit code 2: psql: fe_sendauth: no password supplied in /usr/share/nginx/craft/vendor/craftcms/cms/src/errors/ShellCommandException.php:47
Stack trace:
#0 /usr/share/nginx/craft/vendor/craftcms/cms/src/db/Connection.php(561): craft\errors\ShellCommandException::createFromCommand(Object(mikehaertl\shellcommand\Command))
#1 /usr/share/nginx/craft/vendor/craftcms/cms/src/db/Connection.php(308): craft\db\Connection->_executeDatabaseShellCommand(Object(mikehaertl\shellcommand\Command)
...

[brandonkelly]

Thanks for pointing that out, and the PR! Went about the fix slightly differently, so just committed it myself.