Fix a leak in Lobsters benchmark

Profiling the lobsters benchmark I'm seeing a fairly large time spent
joining tags in TaggedLogger.

That intruigued me, and by digging I noticed the requests UUIDs kept
being appended but never removed.

So for every single request we have one more tag, this is skewing
the benchmark a bit, as we spend much more time than we should in
logging.

Author: byroot

benchmarks/lobsters/benchmark.rb

@@ -47,6 +47,7 @@
       puts response_array.inspect
       raise "HTTP status is #{response_array.first} instead of 200 for req #{idx}/#{generator.routes.size}, #{path.inspect}. Is the benchmark app properly set up? See README.md."
     end
+    response_array.last.close # Response might be a Rack::BodyProxy and MUST be closed.
   end
 end