Remove outdated comment

[jepler]

A comment about a possible relaxation of how bytes URLs are treated in Python 3.3 is no longer relevant or useful. Remove it.

[ghost]

All commit authors signed the Contributor License Agreement.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[hauntsaninja]

Maybe this should be updated to say:

# We deliberately require applications that
# handle improperly quoted URLs to do their own
# decoding and encoding.

[jepler]

Belatedly updated per @hauntsaninja's review comment.