Delete 'implementation' keyword from AlgebraicExtensionFunctor constructor if exists

Author: Newtech66

src/sage/categories/pushout.py

@@ -3294,7 +3294,10 @@ def __init__(self, polys, names, embeddings=None, structures=None,
                 if latex_names[i] == latex_variable_name(name):
                     latex_names[i] = None
         self.latex_names = latex_names
-        self.kwds = kwds
+        kwds_self = dict(kwds.items())
+        if 'implementation' in kwds_self:
+            del kwds_self['implementation']
+        self.kwds = kwds_self
 
     def _apply_functor(self, R):
         """