Fix linter errors in devserver_constants.py.

BUG=None
TEST=Unit tests.

Change-Id: I75ec6ed7ee3746cf009f84c45d8661bfde3c0228
Reviewed-on: https://chromium-review.googlesource.com/251467
Commit-Queue: Gilad Arnold <garnold@chromium.org>
Trybot-Ready: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
diff --git a/devserver_constants.py b/devserver_constants.py
index f2cdbb6..222a1e5 100644
--- a/devserver_constants.py
+++ b/devserver_constants.py
@@ -14,7 +14,7 @@
 GS_RELEASES_DIR = 'gs://chromeos-releases'
 GS_CHANNEL_DIR = GS_RELEASES_DIR + '/%(channel)s-channel/%(board)s/'
 
-VERSION = '[-0-9\.]+'
+VERSION = r'[-0-9\.]+'
 VERSION_RE = 'R%s' % VERSION
 
 STAGED_BUILD_REGEX = '/static/(?P<build>.*-.*/%s)/.*' % VERSION_RE
@@ -29,10 +29,10 @@
 TEST_IMAGE_FILE = 'chromiumos_test_image.bin'
 
 ALL_IMAGES = (
-  BASE_IMAGE_FILE,
-  IMAGE_FILE,
-  RECOVERY_IMAGE_FILE,
-  TEST_IMAGE_FILE,
+    BASE_IMAGE_FILE,
+    IMAGE_FILE,
+    RECOVERY_IMAGE_FILE,
+    TEST_IMAGE_FILE,
 )
 
 #### Update files