Cope with proposed change in gdal.Open (gdal/pull/14763)

[neilflood]

Upcoming GDAL pull request OSGeo/gdal#14763 will cause a change in behaviour of gdal.Open. We rely on the old behaviour in rios.applier.readAllImgInfo, where we expect that the rios.fileinfo.ImageInfo class will raise an exception if called on a vector file. Under the new behaviour, this would no longer be true.

This PR changes the ImageInfo constructor to explicitly use gdal.OpenEx with suitable flags to reproduce the expected behaviour. This appears to work fine under current versions of GDAL.

I think this is the only place that should be affected by the change, most uses of gdal.Open should be fine.

[neilflood]

I will leave this PR tentative, until:

• I figure out why the ubuntu-no-conda test is failing (something about a version conflict between numpy and gdal, I think
• the GDAL PR gets merged, or otherwise becomes more solid