Relicense GPL-2.0-only files to GPL-2.0-or-later

Laurent is the sole contributor.

debug/autotests/akonadisearchdebugdialogtest.cpp

 /*
   SPDX-FileCopyrightText: 2014-2020 Laurent Montel <montel@kde.org>
 
-  SPDX-License-Identifier: GPL-2.0-only
+  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "akonadisearchdebugdialogtest.h"

debug/autotests/akonadisearchdebugdialogtest.h

 /*
   SPDX-FileCopyrightText: 2014-2020 Laurent Montel <montel@kde.org>
 
-  SPDX-License-Identifier: GPL-2.0-only
+  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #ifndef AKONADISEARCHDEBUGDIALOGTEST_H

debug/autotests/akonadisearchdebugsearchpathcomboboxtest.cpp

 /*
   SPDX-FileCopyrightText: 2014-2020 Laurent Montel <montel@kde.org>
 
-  SPDX-License-Identifier: GPL-2.0-only
+  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "akonadisearchdebugsearchpathcomboboxtest.h"

debug/autotests/akonadisearchdebugsearchpathcomboboxtest.h

 /*
   SPDX-FileCopyrightText: 2014-2020 Laurent Montel <montel@kde.org>
 
-  SPDX-License-Identifier: GPL-2.0-only
+  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #ifndef AKONADISEARCHDEBUGSEARCHPATHCOMBOBOXTEST_H

debug/autotests/akonadisearchdebugwidgettest.cpp

 /*
   SPDX-FileCopyrightText: 2014-2020 Laurent Montel <montel@kde.org>
 
-  SPDX-License-Identifier: GPL-2.0-only
+  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "akonadisearchdebugwidgettest.h"

debug/autotests/akonadisearchdebugwidgettest.h

 /*
   SPDX-FileCopyrightText: 2014-2020 Laurent Montel <montel@kde.org>
 
-  SPDX-License-Identifier: GPL-2.0-only
+  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #ifndef AKONADISEARCHDEBUGWIDGETTEST_H

debug/tests/akonadisearchdebug_dialog_gui.cpp

 /*
   SPDX-FileCopyrightText: 2014-2020 Laurent Montel <montel@kde.org>
 
-  SPDX-License-Identifier: GPL-2.0-only
+  SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "../akonadisearchdebugdialog.h"