Revert "Move scm.py to lib/"

This reverts commit 688adfe2765e262aea9563b75a212e92ad35acfc.

Reason for revert: breaks try jobs

Original change's description:
> Move scm.py to lib/
>
> It belongs there.
>
> Change-Id: I286b50c43c587c39557fc508175efbd4b0f51d51
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4289680
> Reviewed-by: Joanna Wang <jojwang@chromium.org>
> Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>

Change-Id: I662907b8bb4b2e7db82409bd34c3905db7961a12
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4300261
Commit-Queue: Josip Sokcevic <sokcevic@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
diff --git a/metrics_utils.py b/metrics_utils.py
index cafe479..e1757bc 100644
--- a/metrics_utils.py
+++ b/metrics_utils.py
@@ -7,7 +7,7 @@
 
 import re
 import os
-from lib import scm
+import scm
 import subprocess2
 import sys