Fix invalid use of try-catch

Its try-except in Python.

Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/git_config.py b/git_config.py
index 36e8d93..a5b5b4d 100644
--- a/git_config.py
+++ b/git_config.py
@@ -388,7 +388,7 @@
     try:
       os.kill(p.pid, SIGTERM)
       p.wait()
-    catch OSError:
+    except OSError:
       pass
   _ssh_cache.clear()