This breaks each call out onto its own line, so that it's much easier to
see where each call starts and how they differ. E.g. previously the output
would be:
Expected spy foo to have been called with [ 'bar', 'baz', 'qux' ] but actual calls were [ [ 42, 'wibble' ], [ 'bar' 'qux' ], [ 'grault '] ]
Now it's:
Expected spy foo to have been called with:
[ 'bar', 'baz', 'qux' ]
but actual calls were:
[ 42, 'wibble' ],
[ 'bar' 'qux' ],
[ 'grault '].