Fix the lambdify tensorflow doctest
Fix the lambdify tensorflow doctest

The doctest fails because it tries to use the SymPy printers to print the
tensorflow object, which fails because it uses the printer for the SymPy
Tensor object.

As a workaround, just print it directly in the doctest.

kaushik94/sympy,kaushik94/sympy,kaushik94/sympy