By Alek Arend Rob Gronkowski took to Twitter on Friday morning, but not because of an update on his football future. The entire NFL community is awaiting an answer from Gronk regarding his future in the NFL. The all-time great, in the meantime, is having some fun teasing fans lately. On Friday morning, though, Gronkowski actually kept things serious. He sent Bruce Arians a heartfelt message following his retirement earlier this week. Gronkowski is clearly going to miss him. “Thanks for the last 2 great years Coach, hopefully they let you keep riding around in your cart always keeping it real,”…