Clean Code: Python

Fix issues found by flake8-bugbear:

* Unused loop variables
* assert statements in non-test code
* mixing test code with production code
* mark one excessive test which takes ~10min to run
  as 'slow'

95_Weekday/python/weekday.py

@@ -142,7 +142,7 @@ def calculate_day_of_week(year, month, day):
 
 
 def end():
-    for i in range(5):
+    for _ in range(5):
         print()
 
 
@@ -259,26 +259,6 @@ def main():
     end()
 
 
-def test_weekday_calc(year, month, day):
-    dt = datetime.date(year, month, day)
-    python_weekday = dt.weekday()  # Monday = 0, Sunday = 6
-
-    basic_weekday = calculate_day_of_week(year, month, day)  # Sunday = 1, Saturday = 7
-
-    if ((python_weekday + 2) % 7) != (basic_weekday % 7):
-        print(f"testing yr {year} month {month} day {day}")
-        print(f"python says {python_weekday}")
-        print(f"BASIC says {basic_weekday}")
-        assert False
-
-
-def test_harness():
-    for yr in range(1600, 2021):
-        for m in range(1, 12):
-            for d in range(1, 28):
-                test_weekday_calc(yr, m, d)
-
-
 if __name__ == "__main__":
     main()