Enable imshow to take GpuMat inputs in Python

modules/python/src2/hdr_parser.py

@@ -958,7 +958,9 @@ class CppHeaderParser(object):
                         else:
                             decls.append(decl)
 
-                            if self._generate_gpumat_decls and "cv.cuda" in decl[0]:
+                            if self._generate_gpumat_decls and ("cv.cuda" in decl[0] or decl[0] in [
+                                "cv.imshow", # https://github.com/opencv/opencv/issues/18553
+                            ]):
                                 # If function takes as one of arguments Mat or vector<Mat> - we want to create the
                                 # same declaration working with GpuMat
                                 args = decl[3]