abandon_stale: fix style warnings from flake8

Change-Id: I7d12bc2e9edc0fbbbb7e0aea61b4c7118d99fb2d

contrib/abandon_stale.py

diff --git a/contrib/abandon_stale.py b/contrib/abandon_stale.py
index 6fd951b..cb1cc23 100755
--- a/contrib/abandon_stale.py
+++ b/contrib/abandon_stale.py
@@ -200,7 +200,7 @@
 
         try:
             gerrit.post("/changes/" + change_id + "/abandon",
-                        json={"message" : "%s" % abandon_message})
+                        json={"message": "%s" % abandon_message})
             abandoned += 1
         except Exception as e:
             errors += 1
@@ -209,5 +209,6 @@
     if not options.dry_run:
         logging.info("Abandoned %d changes. %d errors.", abandoned, errors)
 
+
 if __name__ == "__main__":
     sys.exit(_main())