Redirect pluggable-transports to GitLab

I've migrated these repositories:

gitolite	gitlab	fate
pluggable-transports/httpsproxy.git	tpo/anti-censorship/pluggable-transports/httpsproxy	archive
pluggable-transports/obfs4.git	tpo/anti-censorship/pluggable-transports/lyrebird	migrate
pluggable-transports/obfsproxy.git	tpo/anti-censorship/pluggable-transports/obfsproxy	archive
pluggable-transports/obfsproxy-legacy.git	tpo/anti-censorship/pluggable-transports/obfsproxy-legacy	archive
pluggable-transports/pyptlib.git	tpo/anti-censorship/pluggable-transports/pyptlib	archive
pluggable-transports/snowflake.git	tpo/anti-censorship/pluggable-transports/snowflake	migrate
pluggable-transports/snowflake-mobile.git	tpo/anti-censorship/pluggable-transports/snowflake-mobile	migrate
pluggable-transports/snowflake-webext.git	tpo/anti-censorship/pluggable-transports/snowflake-webext	migrate
pluggable-transports/websocket.git	tpo/anti-censorship/pluggable-transports/websocket	archive