Remove dependency for pinned versions.

R-package/DESCRIPTION

@@ -11,9 +11,9 @@ Description: Calculates samples and related classifiers for mapping gradual prob
 License: GPL-3
 Imports:
     BH (<= 1.69.0-1),
-    sf (<= 0.9-0),
-    sp (<= 1.4-4),
-    rgdal (<= 1.5-12),
+    sf,
+    sp,
+    rgdal,
     raster,
     geojsonio,
     maptools,