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/tests/data_query.cpp b/tests/data_query.cpp
index c62c240..1fd461c 100644
--- a/tests/data_query.cpp
+++ b/tests/data_query.cpp
@@ -6,7 +6,7 @@
 */
 
 #include <experimental/iterator>
-#include "trompeloeil_doctest.h"
+#include "trompeloeil_doctest.hpp"
 
 #ifdef sysrepo_BACKEND
 #include "sysrepo_access.hpp"