[calls] tests: mock-contacts-provider: Add license header

[Evangelos Ribeiro Tzaras <devrtz src gnome org>]

commit 72adee492293be2aa47f8727f9a96f80ae24ca4b
Author: Evangelos Ribeiro Tzaras <devrtz fortysixandtwo eu>
Date:   Mon Jan 31 11:05:23 2022 +0100

    tests: mock-contacts-provider: Add license header

 tests/mock-contacts-provider.h | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/tests/mock-contacts-provider.h b/tests/mock-contacts-provider.h
index dc85931c..431a53c7 100644
--- a/tests/mock-contacts-provider.h
+++ b/tests/mock-contacts-provider.h
@@ -1,3 +1,12 @@
+/*
+ * Copyright (C) 2021 Purism SPC
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * Author: Evangelos Ribeiro Tzaras <devrtz fortysixandtwo eu>
+ *
+ */
+
 #pragma once
 
 #include "calls-contacts-provider.h"