docs: add missing source links to 4 solutions

solutions/python/practice22.py

@@ -1,4 +1,5 @@
-#----- Pascal Triangle -----#
+# Problem: Pascal Triangle
+# Source: https://leetcode.com/problems/pascals-triangle/
 
 ## Prints Pascal's Triangle with the number of rows entered by the user.
 # Each row starts and ends with 1.

solutions/python/practice228.py

@@ -1,4 +1,6 @@
-# py.checkio - Subject is Stressful
+# Problem: Stressful Subject
+# Source: https://py.checkio.org/en/mission/stressful-subject/
+
 
 def is_stressful(subj: str) -> bool:
     if subj.isupper():

solutions/python/practice252.py

@@ -1,4 +1,5 @@
-# FizzBuzz with Twist
+# Problem: FizzBuzz with Twist
+# Source: https://leetcode.com/problems/fizz-buzz/
 
 def fizzbuzzpop(n):
     res = ""

solutions/python/practice255.py

@@ -1,4 +1,5 @@
-# Coin Change (Minimum Coins)
+# Problem: Coin Change (Minimum Coins)
+# Source: https://leetcode.com/problems/coin-change/
 
 def change(n):
     coins = [50, 20, 10, 5, 1]