tests: Apply coding style to unit tests

tests/unittests/xmpp/stub_avatar.c

@@ -2,7 +2,7 @@
 #include <glib.h>
 #include <stdlib.h>
 
-void avatar_pep_subscribe(void){};
+void avatar_pep_subscribe(void) {};
 
 gboolean
 avatar_get_by_nick(const char* nick, gboolean open)

tests/unittests/xmpp/stub_xmpp.c

@@ -309,8 +309,8 @@ presence_sub_request_exists(const char* const bare_jid)
 }
 
 // iq functions
-void iq_disable_carbons(){};
-void iq_enable_carbons(){};
+void iq_disable_carbons() {};
+void iq_enable_carbons() {};
 void
 iq_send_software_version(const char* const fulljid)
 {