Removed spgrass6, which has been removed from CRAN, from description file. It was producing an installation error. I did not remove other references to grass 6 in code.

ryanrbart · ryanrbart · commit 99a06a6801a0 · 2022-05-31T17:09:31.000-07:00
diff --git a/DESCRIPTION b/DESCRIPTION
@@ -14,7 +14,6 @@ LazyData: true
 RoxygenNote: 7.1.1
 Imports:
   raster,
-  spgrass6,
   rgrass7,
   rgdal,
   igraph,
