input: Write a python function to count the occurrences of each character in a string using the collections.Counter module.
  assert count_characters('mississippi') == {'i': 4, 's': 4, 'p': 2, 'm': 1}
  assert count_characters('hello') == {'l': 2, 'h': 1, 'e': 1, 'o': 1}
  assert count_characters('banana') == {'a': 3, 'n': 2, 'b': 1}
output: from collections import Counter
  
  def count_characters(s):
      return dict(Counter(s))