🚨 Fix warning: assigned but unused variable - k (#953)

Author: joeldrapper

lib/phlex/fifo.rb

@@ -36,7 +36,7 @@ def []=(key, value)
 			@bytesize += value.bytesize
 
 			while @bytesize > @max_bytesize
-				k, v = @store.shift
+				_k, v = @store.shift
 				@bytesize -= v[1].bytesize
 			end
 		end