Bump rack from 1.3.3 to 1.6.12 in /6.006/ps3/circuit2/visualizer#1

dependabot[bot] wants to merge 1 commit intomasterryankav/MIT:masterfrom

dependabot/bundler/6.006/ps3/circuit2/visualizer/rack-1.6.12ryankav/MIT:dependabot/bundler/6.006/ps3/circuit2/visualizer/rack-1.6.12Copy head branch name to clipboard