Fix typo from previous commit.

Remove leftover colon from end of line that's no longer a
conditional check.

BUG=None
TEST=None

Change-Id: I3cbcc5f18280adb3044386df205de7309c7a7855
Reviewed-on: https://chrome-internal-review.googlesource.com/217440
Reviewed-by: Yunlian Jiang <yunlian@google.com>
Commit-Queue: Caroline Tice <cmtice@google.com>
Tested-by: Caroline Tice <cmtice@google.com>
diff --git a/test_toolchains.py b/test_toolchains.py
index 6c6ce63..2bcb617 100755
--- a/test_toolchains.py
+++ b/test_toolchains.py
@@ -304,7 +304,7 @@
         label = self._BuildAndImage(label)
       labels.append(label)
     self._FinishSetup()
-    self._TestLabels(labels):
+    self._TestLabels(labels)
     self._SendEmail()
     # Only try to copy the image files if the test runs ran successfully.
     self._CopyWeeklyReportFiles(labels)