fix(pillar_from_files): use `{}` pillar files to ensure tests pass

test/salt/pillar/debian.sls

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# vim: ft=yaml
+---
+php: {}

test/salt/pillar/redhat.sls

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# vim: ft=yaml
+---
+php: {}

test/salt/pillar/suse.sls

@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# vim: ft=yaml
+---
+php: {}