bitlbee-discord: Update to 0.4.3

Alcaro (1):
      Fix paste_buffer

Alex Schroeder (1):
      Add BITLBEE_LIBS to discord_la_LDFLAGS

Artem Savkov (9):
      Don't wait for GUILD_SYNC on login
      Remove pending sync var
      Per-channel sync
      Sync private groups as well
      Call imcb_connected only after we parsed the whole READY message

David Aaron Fendley (1):
      Correct command in README

(nia)