input: Write a python function to filter people over 21 years old from a dictionary.
  assert filter_adults({'John': 20, 'Jane': 40, 'Alex': 18, 'Peter': 45}) == {'Jane': 40, 'Peter': 45}
  assert filter_adults({'Anna': 22, 'Tom': 19, 'Mike': 30}) == {'Anna': 22, 'Mike': 30}
  assert filter_adults({'Chris': 20, 'Pat': 21, 'Sam': 25}) == {'Sam': 25}
output: def filter_adults(people):
      return {name: age for name, age in people.items() if age > 21}