increase HTTP timeout for initial post publication to 60 seconds

After a while, experiments made some publication events time-out.
Increasing the timeout just in case, although it i likely to be a mere symptom but the core fault.

app/Experiment.hs

@@ -40,7 +40,7 @@ executeSchedule :: Int  -- ^ speedup factor
                 -> IO ()
 executeSchedule speedup events = do
     -- initialise HTTP manager
-    httpMan <- HTTP.newManager HTTP.defaultManagerSettings
+    httpMan <- HTTP.newManager $ HTTP.defaultManagerSettings { HTTP.managerResponseTimeout = HTTP.responseTimeoutMicro 60000000 }
     forM_ events $ \(delay, tag, (pubHost, pubPort)) -> do
         _ <- forkIO $
             clientPublishPost httpMan pubHost pubPort ("foobar #" <> tag)