input: Write a python function to find the minimum of a 2-variable function using `scipy.optimize.fmin`.
  assert find_minimum(lambda x, y: 3*x**2 + 2*x*y + 5*y**2, 0, 0) == (0.0, 0.0)
  assert find_minimum(lambda x, y: (x-1)**2 + (y-1)**2, 2, 2) == (1.0, 1.0)
  assert find_minimum(lambda x, y: x**2 + y**2, -1, -1) == (0.0, 0.0)
output: from scipy.optimize import fmin
  
  def find_minimum(func, x0, y0):
      def wrapper(vars):
          x, y = vars
          return func(x, y)
      
      result = fmin(wrapper, [x0, y0], disp=False)
      return tuple(result)