Require Python 3.8+

All users of Chromite should be migrated to 3.8+.  We can begin to
assert this.

BUG=b:187794810
TEST=CQ

Change-Id: I0a082c71ffd1d7f3754ec87768e63982aeb3f086
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4509034
Tested-by: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
diff --git a/scripts/wrapper3.py b/scripts/wrapper3.py
index f77f9ed..28c0572 100755
--- a/scripts/wrapper3.py
+++ b/scripts/wrapper3.py
@@ -19,10 +19,10 @@
 
 
 # Assert some minimum Python versions as we don't test or support any others.
-# We only support Python 3.6+.
-if sys.version_info < (3, 6):
+# We only support Python 3.8+.
+if sys.version_info < (3, 8):
     print(
-        '%s: chromite: error: Python-3.6+ is required, but "%s" is "%s"'
+        '%s: chromite: error: Python-3.8+ is required, but "%s" is "%s"'
         % (sys.argv[0], sys.executable, sys.version.replace("\n", " ")),
         file=sys.stderr,
     )