BUG: fix viewer series selection parameter

SeriesInstanceUID changed to SeriesInstanceUIDs, see
https://docs.ohif.org/migration-guide/from-3p7-to-3p8#studyinstanceuid-in-the-url-param

Author: fedorov

idc_index/index.py

@@ -508,7 +508,7 @@ def get_viewer_URL(
                 ohif_v2, ohif_v3, or slim. If not provided, default viewers will be used.
 
         Returns:
-            string containing the IDC viewer URL for the given SeriesInstanceUID
+            string containing the IDC viewer URL for the requested selection
         """
 
         if seriesInstanceUID is None and studyInstanceUID is None:
@@ -581,7 +581,7 @@ def get_viewer_URL(
             if seriesInstanceUID is None:
                 viewer_url = f"https://viewer.imaging.datacommons.cancer.gov/v3/viewer/?StudyInstanceUIDs={studyInstanceUID}"
             else:
-                viewer_url = f"https://viewer.imaging.datacommons.cancer.gov/v3/viewer/?StudyInstanceUIDs={studyInstanceUID}&SeriesInstanceUID={seriesInstanceUID}"
+                viewer_url = f"https://viewer.imaging.datacommons.cancer.gov/v3/viewer/?StudyInstanceUIDs={studyInstanceUID}&SeriesInstanceUIDs={seriesInstanceUID}"
         elif viewer_selector == "volview":
             # TODO! Not implemented yet
             viewer_url = None