Add __future__ imports to error reporter code.

scripts/ErrorReporter/error_dialog_app.py

@@ -4,6 +4,8 @@
 #     NScD Oak Ridge National Laboratory, European Spallation Source
 #     & Institut Laue - Langevin
 # SPDX - License - Identifier: GPL - 3.0 +
+from __future__ import (absolute_import, print_function)
+
 import sys
 import argparse
 

scripts/ErrorReporter/error_report_presenter.py

@@ -4,6 +4,8 @@
 #     NScD Oak Ridge National Laboratory, European Spallation Source
 #     & Institut Laue - Langevin
 # SPDX - License - Identifier: GPL - 3.0 +
+from __future__ import (absolute_import, print_function)
+
 import os
 
 from mantid.kernel import ErrorReporter, UsageService, ConfigService

scripts/ErrorReporter/errorreport.py

@@ -4,6 +4,8 @@
 #     NScD Oak Ridge National Laboratory, European Spallation Source
 #     & Institut Laue - Langevin
 # SPDX - License - Identifier: GPL - 3.0 +
+from __future__ import (absolute_import, print_function)
+
 from qtpy import QtGui, QtCore, QtWidgets
 from qtpy.QtCore import Signal