Fix reporting of h5py version in the test runner

Some older versions of h5py do not have an `h5py.__version__` attribute.  This is of course a bug on its part, but since we skip it if `h5py.__version__` raises an exception we report it as not available, even though the h5py tests still run.

This uses `h5py.version.version` instead.  I checked the latest version of h5py and even it just defines:

```
__version__ = version.version
```

so this should be fine.