autotest: Add pyshark for wifi packet capture analysis in lab machines.

Adding pyshark and it's dependencies for packet capture analysis done
in Wifi tests in Lab machines.

BUG=chromium:470708
TEST=`python utils/build_externals.py`
DEPLOY=build_externals

Change-Id: Id4800ce6f3f57f0840273cde0d9fa86c12a1dd96
Reviewed-on: https://chromium-review.googlesource.com/263121
Reviewed-by: Roshan Pius <rpius@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
Commit-Queue: Roshan Pius <rpius@chromium.org>
Tested-by: Roshan Pius <rpius@chromium.org>
1 file changed