Fix deprecation warning for Sympy 1.7

We have to try from newest to oldest import to avoid deprecation warnings.

They added the old import again, but with a deprecation warning.

pystencils/interpolation_astnodes.py

@@ -352,7 +352,7 @@ class InterpolatorAccess(TypedSymbol):
     __xnew_cached_ = staticmethod(cacheit(__new_stage2__))
 
     def __getnewargs__(self):
-        return tuple(self.symbol, *self.offsets)
+        return self.symbol, *self.offsets
 
 
 class DiffInterpolatorAccess(InterpolatorAccess):
@@ -397,7 +397,7 @@ class DiffInterpolatorAccess(InterpolatorAccess):
     __xnew_cached_ = staticmethod(cacheit(__new_stage2__))
 
     def __getnewargs__(self):
-        return tuple(self.symbol, self.diff_coordinate_idx, *self.offsets)
+        return self.symbol, self.diff_coordinate_idx, *self.offsets
 
 
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