Tune 9971's fender shot

The board works great with these settings.

Change-Id: Ib5ed83e1ea99ec8aae672ca859d9418144de2829
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/y2020/joystick_reader.cc b/y2020/joystick_reader.cc
index b101337..0fcc5cf 100644
--- a/y2020/joystick_reader.cc
+++ b/y2020/joystick_reader.cc
@@ -187,7 +187,7 @@
         finisher_speed = setpoint_fetcher_->finisher();
       }
     } else if (data.IsPressed(kShootSlow)) {
-      accelerator_speed = 150.0;
+      accelerator_speed = 400.0;
       finisher_speed = 200.0;
     }