read_geoid() fails with rasterio.errors.RasterioIOError: HTTP response code: 403

[asjohnston-asf]

read_geoid() is failing to access the geoid files hosted under https://s3-eu-west-1.amazonaws.com/download.agisoft.com/geoids/ . As of this morning, attempting to access any of the three files fails with an HTTP 403 "All access to this object has been disabled" error. Googling that error message suggests the underlying AWS account has been closed.

• https://s3-eu-west-1.amazonaws.com/download.agisoft.com/geoids/geoid_18.tif
• https://s3-eu-west-1.amazonaws.com/download.agisoft.com/geoids/egm2008-1.tif
• https://s3-eu-west-1.amazonaws.com/download.agisoft.com/geoids/egm96-15.tif

Similar to #88 , I expect this will cause all dem stitching attempts to fail.

[asjohnston-asf]

I confirmed the download links at https://www.agisoft.com/downloads/geoids/ are unchanged; the links on that page result in the same error.