aboutDialog: Update credits

Author: tchx84

src/widgets/aboutDialog.ui

@@ -7,7 +7,7 @@
     <property name="type_hint">dialog</property>
     <property name="program_name">Flatseal</property>
     <property name="version">1.7.5</property>
-    <property name="copyright">© 2020-2021 Martin Abente Lahaye</property>
+    <property name="copyright">© 2020-2022 Martin Abente Lahaye</property>
     <property name="comments" translatable="yes">Flatseal is a graphical utility to review and modify permissions from your Flatpak applications.</property>
     <property name="website">https://github.com/tchx84/flatseal</property>
     <property name="website_label">Flatseal</property>