Support `With` statement for cursor class

[Chaho12]

Describe the feature

In dbapi.py, i notice that Connection class DO have __enter__, __exit__, but Cursor class does not.

Is there a reason for why it doesn't have those classes? so that users can use with with statement?

with connection.cursor() as cursor:
    cursor.execute("SELECT * FROM table")
    results = cursor.fetchall()

Describe alternatives you've considered

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

[hashhar]

Please add it, no specific reason why it's not there.

[hashhar]

Fixed by merging #537