cli: cros lint/format: add support for .vpython manifests

Treat these as plain text files.

BUG=None
TEST=CQ passes

Change-Id: I8c0abff617c70a937ccc947e5e938cdffb06a0df
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4706148
Commit-Queue: Cindy Lin <xcl@google.com>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Cindy Lin <xcl@google.com>
diff --git a/scripts/run_tests.vpython3 b/scripts/run_tests.vpython3
index 74b21a2..a2a875e 100644
--- a/scripts/run_tests.vpython3
+++ b/scripts/run_tests.vpython3
@@ -322,4 +322,4 @@
 wheel: <
   name: "infra/python/wheels/flask-py3"
   version: "version:2.0.2"
->
\ No newline at end of file
+>