[FIX] Type hint for precision dependant Float, Int (#111)

* Fix the type hint of Float, Int

* Attempt using TypeAlias

ndsl/dsl/typing.py

@@ -1,5 +1,5 @@
 import os
-from typing import Tuple, Union, cast
+from typing import Tuple, TypeAlias, Union, cast
 
 import gt4py.cartesian.gtscript as gtscript
 import numpy as np
@@ -34,13 +34,13 @@ def get_precision() -> int:
 # We redefine the type as a way to distinguish
 # the model definition of a float to other usage of the
 # common numpy type in the rest of the code.
-NDSL_32BIT_FLOAT_TYPE = np.float32
-NDSL_64BIT_FLOAT_TYPE = np.float64
-NDSL_32BIT_INT_TYPE = np.int32
-NDSL_64BIT_INT_TYPE = np.int64
+NDSL_32BIT_FLOAT_TYPE: TypeAlias = np.float32
+NDSL_64BIT_FLOAT_TYPE: TypeAlias = np.float64
+NDSL_32BIT_INT_TYPE: TypeAlias = np.int32
+NDSL_64BIT_INT_TYPE: TypeAlias = np.int64
 
 
-def global_set_precision() -> type:
+def global_set_precision() -> Tuple[TypeAlias, TypeAlias]:
     """Set the global precision for all references of
     Float and Int in the codebase. Defaults to 64 bit."""
     global Float, Int