input: Write a function to search a string in a paragraph and return a message if found or not.
  assert search_string("The quick brown fox jumps over the lazy dog", 'fox') == "Found the string 'fox'"
  assert search_string("The quick brown fox jumps over the lazy dog", 'cat') == "Sorry, string not found"
  assert search_string("Lorem ipsum dolor sit amet, consectetur adipiscing elit", 'dolor') == "Found the string 'dolor'"
output: def search_string(paragraph, search_term):
      if search_term in paragraph:
          return f"Found the string '{search_term}'"
      else:
          return "Sorry, string not found"