resolve scipy 1.8.0 io.netcdf deprecation warning (#3451)

wrappers/python/openmm/app/internal/amber_file_parser.py

@@ -1433,10 +1433,15 @@ class AmberNetcdfRestart(object):
     >>> coordinates = f.coordinates
     """
     def __init__(self, filename, asNumpy=False):
+        try:
+            from scipy.io import NetCDFFile
+        except ImportError:
+            # scipy < 1.8.0
             try:
                 from scipy.io.netcdf import NetCDFFile
             except ImportError:
-            raise ImportError('scipy is necessary to parse NetCDF restarts')
+                raise ImportError('scipy is necessary to parse NetCDF '
+                                  'restarts')
 
         self.filename = filename
         self.velocities = self.boxVectors = self.time = None

wrappers/python/tests/TestAmberInpcrdFile.py

@@ -5,12 +5,16 @@ from openmm import *
 from openmm.unit import *
 import openmm.app.element as elem
 try:
+    from scipy.io import NetCDFFile
+    SCIPY_IMPORT_FAILED = False
+except ImportError:
+    try:
+        # scipy < 1.8.0
         from scipy.io import netcdf
         SCIPY_IMPORT_FAILED = False
-except:
+    except:
         SCIPY_IMPORT_FAILED = True
 
-
 def compareByElement(array1, array2, cmp):
     for x, y in zip(array1, array2):
         cmp(x, y)