ms-tweaks-utils: Ignore -Wformat-nonliteral warning

"-Wformat=2" includes "-Wformat-nonliteral", which is now triggered by code in src/pmos-tweaks/ms-tweaks-utils.c

Error message

../phosh-mobile-settings-0.49.0/src/pmos-tweaks/ms-tweaks-utils.c:76:3: warning: 'format' attribute argument not supported: gnu_printf [-Wignored-attributes]
   76 | [[gnu::format (gnu_printf, 4, 5)]]
      |   ^
../phosh-mobile-settings-0.49.0/src/pmos-tweaks/ms-tweaks-utils.c:88:34: error: format string is not a string literal [-Werror,-Wformat-nonliteral]
   88 |   g_logv (log_domain, log_level, format_with_prefix, args);
      |                                  ^~~~~~~~~~~~~~~~~~
1 warning and 1 error generated.