Code coach Day of the week

Question

I wrote this code but it works for all test cases but one (test case #5) and I don't know why. Can you help me?
Here is the problem:
You receive a date and need to know what day of the week it is.
Task:
Create a program that takes in a string containing a date, and outputs the day of the week.
Input Format:
A string containing a date in either "MM/DD/YYYY" format or "Month Day, Year" format.
Output Format:
A string containing the day of the week from the provided date.
Sample Input:
11/19/2019
Sample Output:
Tuesday
Here is the code I wrote:
https://code.sololearn.com/cnzcUzQW582i

Answer 1

It works but only for some of the test cases. Some of them are with the following format:
July 20, 2020
But thank you very much. It help me to imrpve my knowledge.

Answer 2

Thank you very much for your help!