Set retention roller current limits in shooter.cc

This lets us turn down the current to 2 amps if we are loaded, if not we
want to go back up to 5 amps.

Signed-off-by: Maxwell Henderson <mxwhenderson@gmail.com>
Change-Id: Ib164af63052dd00533a75fee8b1f89073dbec749
diff --git a/y2024/constants/constants.fbs b/y2024/constants/constants.fbs
index 3b4942d..df9a6fb 100644
--- a/y2024/constants/constants.fbs
+++ b/y2024/constants/constants.fbs
@@ -82,6 +82,7 @@
   altitude_stator_current_limit:double (id: 17);
   retention_roller_supply_current_limit:double (id: 18);
   retention_roller_stator_current_limit:double (id: 19);
+  slower_retention_roller_stator_current_limit:double (id: 20);
 }
 
 table TransferRollerVoltages {