LibGWeather 3.9.1 Brings Fixes for METAR and Yahoo Backends

LibGWeather 3.9.1 fixes various issues found in the Yahoo, METAR and yr.no backends, and adds a new API to flush the cache to disk (available only for language bindings with a GC). Moreover, the default measure units are now derived from LC_MEASUREMENTS, instead of LC_MESSAGES, respecting the configuration from the Region & Language section of the Control Center panel. Last but not least, GWeatherLocationEntry will autocomplete when pressing the Enter key, but only if activates-default is true, GWeatherInfo enables automatic disk caching of gzip encoding and network request, and lots of translations have been updated.