Update merlin.core.compat to use HAS_GPU and add add'l libraries (#262)

Author: karlhigley

merlin/core/compat.py

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2022, NVIDIA CORPORATION.
+# Copyright (c) 2023, NVIDIA CORPORATION.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -17,11 +17,6 @@
 # pylint: disable=unused-import
 import os
 
-try:
-    from numba import cuda
-except ImportError:
-    cuda = None
-
 from dask.distributed.diagnostics import nvml
 
 
@@ -50,21 +45,42 @@ def _get_gpu_count():
 
 HAS_GPU = _get_gpu_count() > 0
 
+if HAS_GPU:
+    try:
+        from numba import cuda
+    except ImportError:
+        cuda = None
+
+    try:
+        import cudf
+    except ImportError:
+        cudf = None
+
+    try:
+        import cupy
+    except ImportError:
+        cupy = None
+
+    try:
+        import dask_cudf
+    except ImportError:
+        dask_cudf = None
+
+else:
+    cuda = None
+    cudf = None
+    cupy = None
+    dask_cudf = None
 
 try:
     import numpy
 except ImportError:
     numpy = None
 
 try:
-    import cupy
+    import pandas
 except ImportError:
-    cupy = None
-
-try:
-    import cudf
-except ImportError:
-    cudf = None
+    pandas = None
 
 try:
     import tensorflow