remove unused lodash from server.js
remove unused lodash from server.js

parasgithub/PrairieLearn,parasgithub/PrairieLearn,rbessick5/PrairieLearn,rbessick5/PrairieLearn,jakebailey/PrairieLearn,rbessick5/PrairieLearn,mwest1066/PrairieLearn,mwest1066/PrairieLearn,parasgithub/PrairieLearn,parasgithub/PrairieLearn,jakebailey/PrairieLearn,tbretl/PrairieLearn,tbretl/PrairieLearn,mwest1066/PrairieLearn,tbretl/PrairieLearn,jakebailey/PrairieLearn,tbretl/PrairieLearn,mwest1066/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,jakebailey/PrairieLearn,rbessick5/PrairieLearn,rbessick5/PrairieLearn,tbretl/PrairieLearn