Update upgrade info for pihole app

charts/pihole/upgrade_info.json

@@ -1 +1 @@
-{"filename":  "ix_values.yaml", "keys": ["image"]}
+{"filename":  "ix_values.yaml", "keys": ["image"], "test_filename": "test_values.yaml"}

test/pihole/upgrade_info.json

@@ -1 +1 @@
-{"filename":  "ix_values.yaml", "keys": ["image"]}
+{"filename":  "ix_values.yaml", "keys": ["image"], "test_filename": "test_values.yaml"}