Merge pull request #1913 from Shaikh-Ubaid/add_missing_slots

lpython.py: Add missing slots

Author: certik

src/runtime/lpython/lpython.py

@@ -9,7 +9,7 @@
         "overload", "ccall", "TypeVar", "pointer", "c_p_pointer", "Pointer",
         "p_c_pointer", "vectorize", "inline", "Union", "static",
         "packed", "Const", "sizeof", "ccallable", "ccallback", "Callable",
-        "Allocatable"]
+        "Allocatable", "In", "Out", "InOut", "dataclass"]
 
 # data-types