cros: start pushing people to 3.11

As we shift CrOS to 3.11 entirely, we'll stop testing 3.8, so start
pushing people to upgrade to 3.11.  This way when we eventually
require 3.11, people won't be surprised.

Bug: 318532035
Change-Id: I3be6b4cce56321984ff4aad4f6998660be29550c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6165449
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Alex Klein <saklein@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>

cros

@@ -19,7 +19,7 @@ import sys
 from typing import List, NamedTuple, Optional, Tuple
 
 # Min version of Python that we *want*.  We warn for older versions.
-MIN_PYTHON_VER_SOFT = (3, 8)
+MIN_PYTHON_VER_SOFT = (3, 11)
 # Min version of Python that we *require*.  We abort for older versions.
 MIN_PYTHON_VER_HARD = (3, 8)