talkatu/talkatu

Don't use g_datetime_format_iso8601 as it was added after our minimum glib version

Fallback to just %I:%M %P for the time stamp since g_datetime_format_iso8601 was added after our minimum glib version

Testing Done:
compiled and ran the demo to verify.

Reviewed at https://reviews.imfreedom.org/r/99/
if get_option('vapi')
if not get_option('introspection')
error('Vala generation requires GObject Introspection.')
endif
add_languages('vala')
talkatu_vapi = gnome.generate_vapi('talkatu',
sources : talkatu_gir[0],
packages : [ 'gtk+-3.0' ],
install : true,
gir_dirs : meson.current_build_dir() / '..' / 'talkatu',
)
endif # vala