Update imgaug.py

Modified to work with new numpy versions, see
aleju#859 (comment)

imgaug/imgaug.py

@@ -36,9 +36,11 @@
 # to check if a dtype instance is among these dtypes, use e.g.
 # `dtype.type in  NP_FLOAT_TYPES` do not just use `dtype in NP_FLOAT_TYPES` as
 # that would fail
-NP_FLOAT_TYPES = set(np.sctypes["float"])
-NP_INT_TYPES = set(np.sctypes["int"])
-NP_UINT_TYPES = set(np.sctypes["uint"])
+# Modified to work with new numpy versions, see 
+# https://github.com/aleju/imgaug/issues/859#issue-2593394731
+NP_FLOAT_TYPES = {np.float16, np.float32, np.float64}
+NP_INT_TYPES = {np.int8, np.int16, np.int32, np.int64}
+NP_UINT_TYPES = {np.uint8, np.uint16, np.uint32, np.uint64}
 
 IMSHOW_BACKEND_DEFAULT = "matplotlib"