Upgrade wheels used by WPT (including webdriver tests)

Upstream WPT has recently upgraded to pytest v4:
https://github.com/web-platform-tests/wpt/pull/26704

Also take this chance to upgrade some other wheels used by WPT to the
latest we have in CIPD, and remove a duplicate psutil spec.

Change-Id: I102fd4b6717fdb1b778f92933afb4c7cf74f834a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2592134Reviewed-by: John Chen <johnchen@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837157}

.vpython

@@ -238,12 +238,12 @@ wheel: <
 
 wheel <
   name: "infra/python/wheels/pytest-py2_py3"
-  version: "version:3.6.2"
+  version: "version:4.1.1"
 >
 
 wheel <
   name: "infra/python/wheels/attrs-py2_py3"
-  version: "version:17.4.0"
+  version: "version:18.2.0"
 >
 
 wheel <
@@ -258,12 +258,12 @@ wheel <
 
 wheel <
   name: "infra/python/wheels/scandir/${vpython_platform}"
-  version: "version:1.7"
+  version: "version:1.9.0"
 >
 
 wheel <
   name: "infra/python/wheels/pluggy-py2_py3"
-  version: "version:0.7.1"
+  version: "version:0.8.1"
 >
 
 wheel <
@@ -275,10 +275,6 @@ wheel <
   name: "infra/python/wheels/funcsigs-py2_py3"
   version: "version:1.0.2"
 >
-wheel: <
-  name: "infra/python/wheels/psutil/${vpython_platform}"
-  version: "version:5.2.2"
->
 
 # Used by:
 #   tools/infra
@@ -329,7 +325,7 @@ wheel: <
 >
 wheel: <
   name: "infra/python/wheels/urllib3-py2_py3"
-  version: "version:1.22"
+  version: "version:1.24.3"
 >
 wheel: <
   name: "infra/python/wheels/blessings-py2_py3"
@@ -349,7 +345,7 @@ wheel: <
 >
 wheel: <
   name: "infra/python/wheels/certifi-py2_py3"
-  version: "version:2018.11.29"
+  version: "version:2020.11.8"
 >
 wheel: <
   name: "infra/python/wheels/chardet-py2_py3"