LibTimeZone: Add method to convert a time zone to a string

Author: https://github.com/trflynn89
Commit: 1c2c98ac5d
Pull-request: https://github.com/SerenityOS/serenity/pull/11799
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibTimeZone/TimeZone.cpp

@@ -9,5 +9,6 @@
 namespace TimeZone {
 
 Optional<TimeZone> __attribute__((weak)) time_zone_from_string(StringView) { return {}; }
+StringView __attribute__((weak)) time_zone_to_string(TimeZone) { return {}; }
 
 }