gitignore: Add __pychache__ dir

That's created by VTY tests running python.

Change-Id: Idb67909ddd5027dbdcbf5a3882d1bb0d4ff9d29e
diff --git a/.gitignore b/.gitignore
index 58be63b..01f4f47 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,6 +32,7 @@
 
 # tests
 .dirstamp
+__pycache__/
 tests/atconfig
 tests/package.m4
 tests/*/*Test