change from_dlpack to _dlpack, remove unused header

Original NumPy Commit: ba8fcbe2ba0a26cd52dfa9bf40dd2e945e5b298f

Author: mattip

array_api_strict/__init__.py

@@ -136,7 +136,7 @@
     empty,
     empty_like,
     eye,
-    from_dlpack,
+    _from_dlpack,
     full,
     full_like,
     linspace,
@@ -155,7 +155,7 @@
     "empty",
     "empty_like",
     "eye",
-    "from_dlpack",
+    "_from_dlpack",
     "full",
     "full_like",
     "linspace",

array_api_strict/_creation_functions.py

@@ -151,7 +151,7 @@ def eye(
     return Array._new(np.eye(n_rows, M=n_cols, k=k, dtype=dtype))
 
 
-def from_dlpack(x: object, /) -> Array:
+def _from_dlpack(x: object, /) -> Array:
     # Note: dlpack support is not yet implemented on Array
     raise NotImplementedError("DLPack support is not yet implemented")