2 Institute Names mistakenly placed in DOI field in WIEWS data, removed

@petergpython @ColinKhoury 2 institute names were found in DOI field in WIEWS data, I removed these from DOI field in this line, replacing with blanks as there is no suitable field to reassign the data.

https://gitlab.croptrust.org/gccs-public/ex_situ_PGRFA_metrics_2nd_crop_batch/-/blob/ea1fc20156802903cef575ef8ca24de1d0d5ded6/1_merge_data.R#L154-L156