fix date in workshop table
fix date in workshop table

ErinBecker/datacarpentry.github.io,ErinBecker/datacarpentry.github.io,ErinBecker/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,ErinBecker/datacarpentry.github.io