Add protobuf-py2_py3 3.13.0 to .vpython.
Add protobuf-py2_py3 3.13.0 to .vpython.

Starting from https://webrtc-review.googlesource.com/c/src/+/194081,
WebRTC's protobuf are using version 3.13.0.1+ but when running on
bots, we see errors that are probably caused by a version mismatch, see
https://ci.chromium.org/p/webrtc/builders/perf/Perf%20Linux%20Trusty/4597.

This CL updates WebRTC's .vpython to use protobuf 3.13.0.

TBR=kwiberg@webrtc.org

No-Try: True
Bug: None
Change-Id: I6bc5e71bacc67dbd9299a9588ddf826778451949
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/194143
Commit-Queue: Mirko Bonadei <d2c43c210eae6feef04f53bae50885e8152edcca@webrtc.org>
Reviewed-by: Andrey Logvin <d1a9cba877864cffb2bba2f18040e3a770e73eed@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#32642}

ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc