remove force of version of taxcalc
remove force of version of taxcalc

- Now that taxcalc uses the latest numpy, we don't have to force a
  version anymore and it should automatically get the latest

zrisher/webapp-public,OpenSourcePolicyCenter/webapp-public,OpenSourcePolicyCenter/PolicyBrain,OpenSourcePolicyCenter/PolicyBrain,OpenSourcePolicyCenter/PolicyBrain,OpenSourcePolicyCenter/PolicyBrain,zrisher/webapp-public,zrisher/webapp-public,OpenSourcePolicyCenter/webapp-public,zrisher/webapp-public,OpenSourcePolicyCenter/webapp-public,OpenSourcePolicyCenter/webapp-public