Move to mozlog 5.0 in .vpython

Bug: 1056722
Change-Id: Ib0155de66b4ec29929799a52968928bcdf94b6db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2087619
Auto-Submit: Luke Z <lpz@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746843}

.vpython

@@ -307,7 +307,7 @@ wheel: <
 >
 wheel: <
   name: "infra/python/wheels/mozlog-py2_py3"
-  version: "version:4.2.0"
+  version: "version:5.0"
 >
 wheel: <
   name: "infra/python/wheels/mozprocess-py2_py3"