Fix test.utils.assertRaisesRegexp() when Regex is a `str`
Fix test.utils.assertRaisesRegexp() when Regex is a `str`

See https://github.com/scality/scality-sproxyd-client/commit/a2888f49d3e341231c17045be9170848b8bbf880
scality/ScalitySproxydSwift,scality/ScalitySproxydSwift