PRESUBMIT: drop python2 usage

We haven't used Python 2 in years.

BUG=None
TEST=CQ passes

Change-Id: I08924e67386a7a499c55a2ea90ebd6b2d7ac2caa
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashmap/+/4240702
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
index 2150455..bd94ae3 100644
--- a/PRESUBMIT.cfg
+++ b/PRESUBMIT.cfg
@@ -1,8 +1,7 @@
 # This project uses BSD/GPLv2 for the license and tabs for indentation.
 
 [Hook Scripts]
-fmap_unittest py2 = python2 ./fmap_unittest.py
-fmap_unittest py3 = python3 ./fmap_unittest.py
+fmap_unittest = ./fmap_unittest.py
 cros lint = cros lint ${PRESUBMIT_FILES}
 
 [Hook Overrides]