Feat/water day python solution -> main

[alangnt]

Hi Codédex team,

This PR adds a working Python solution for today's Water Day 💧 challenge, and updates the README to add a link for the challenge.

Here's the code :

def leaky_pipe(volume, leak, hours, threshold):
  # for each passing hour
  for i in range(hours):
    # we calculate the new volume based on the formula
    volume = volume * (1 - leak / 100)

    # check if treshold
    if volume < threshold:
      # if volume less than threshold, it failed
      return -1

  # otherwise we return the new volume
  # once the loop is over, rounded by 2 decimals
  return round(volume, 2)

Here's how it works :

• for each hour that has passed, we calculate the new volume using the given formula
• if the new volume is below the threshold, that means it failed before time is up, so we return -1
• otherwise we return the new volume rounded by 2 decimals once the loops is over

Have a nice day !