Fix fifo: uniq! is understandably slow.

src/fifo.cr

@@ -30,8 +30,8 @@ class FIFO(V)
 	# NOTE: `#<<(v : V)` is the only function since it's enough for the intended use, feel free to improve this.
 	# WARNING: implementation is extremely simple (3 lines) and not designed to be highly efficient.
 	def <<(v : V) : V?
+		@data.select! { |x| v != v }            # remove dups
 		@data.unshift v                         # push on top of the stack
-		@data.uniq!                             # remove dups
 		@data.pop if @data.size > @max_entries  # remove least recently used entry if `@data` is too big
 	end
 end