make users.uid NOT NULL for PS compat
make users.uid NOT NULL for PS compat

PrairieLearn/PrairieLearnHack,lotrfan/PrairieLearn,PrairieLearn/PrairieLearnHack,mwest1066/PrairieLearn,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,jakebailey/PrairieLearn,parasgithub/PrairieLearn,PrairieLearn/PrairieLearnHack,tbretl/PrairieLearn,jakebailey/PrairieLearn,lotrfan/PrairieLearn,rbessick5/PrairieLearn,kevinwang/PrairieLearn,kevinwang/PrairieLearn,lotrfan/PrairieLearn,lotrfan/PrairieLearn,lotrfan/PrairieLearn,tbretl/PrairieLearn,kevinwang/PrairieLearn,PrairieLearn/PrairieLearnHack,kevinwang/PrairieLearn,rbessick5/PrairieLearn,jakebailey/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,rbessick5/PrairieLearn,parasgithub/PrairieLearn,PrairieLearn/PrairieLearnHack,tbretl/PrairieLearn,lotrfan/PrairieLearn,parasgithub/PrairieLearn,rbessick5/PrairieLearn,kevinwang/PrairieLearn,tbretl/PrairieLearn,mwest1066/PrairieLearn,mwest1066/PrairieLearn,kevinwang/PrairieLearn,rbessick5/PrairieLearn,mwest1066/PrairieLearn,kevinwang/PrairieLearn,parasgithub/PrairieLearn,tbretl/PrairieLearn,jakebailey/PrairieLearn,lotrfan/PrairieLearn,PrairieLearn/PrairieLearnHack