Don't Require gvfs for Flatpak builds

Otherwise we would have to pull gvfs into the "gedit" flatpak
module/container.

See https://docs.fedoraproject.org/en-US/flatpak/tutorial/

gedit.spec

@@ -55,7 +55,9 @@ Requires: python3-gobject >= %{pygo_version}
 # the run-command plugin uses zenity
 Requires: zenity
 Requires: gsettings-desktop-schemas
+%if ! 0%{?flatpak}
 Requires: gvfs
+%endif
 
 # for file triggers
 Requires: glib2 >= 2.45.4-2