Rename .h header files to .hpp

Majority of the project uses .hpp and .h shouldn't be used for C++
header files anyway.

Change-Id: I979ba2d243f8f5dbf45c37237ac4aaf9a733eba8
diff --git a/src/yang_schema.cpp b/src/yang_schema.cpp
index ddd6f37..dddebf5 100644
--- a/src/yang_schema.cpp
+++ b/src/yang_schema.cpp
@@ -10,7 +10,7 @@
 #include <libyang/Tree_Data.hpp>
 #include <libyang/Tree_Schema.hpp>
 #include <string_view>
-#include "UniqueResource.h"
+#include "UniqueResource.hpp"
 #include "utils.hpp"
 #include "yang_schema.hpp"