This change fixes a minor issue in the pylint-2.6.bat wrapper
script and adds a missing dependency on colorama.

With these changes, it looks like pylint-2.6 will now work on Windows.

Bug: 1157676
Change-Id: Ic23fc4cd04bf464034bf5471856fdfb646f66a75
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3018262Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@google.com>