gitignore: add tests/db_upgrade/*.dump

Change-Id: I0dca7a94883bbe69151d919ae204edfff12288ab
diff --git a/.gitignore b/.gitignore
index 93f65e9..8d4b450 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,6 +50,7 @@
 tests/gsup/gsup_test
 tests/db/db_test
 tests/hlr_vty_test.db*
+tests/db_upgrade/*.dump
 
 # manuals
 doc/manuals/*.html