Csv validation

[rokroskar]

• adds a github action to validate CSV files
• fixes missing fields in TI data

Since this is a fork, the action won't run on the PR - but you can see it here: https://github.com/rokroskar/covid_19/runs/521628375?check_suite_focus=true

addresses #22

[rokroskar]

Actually - if this is to be a required status check to pass we probably want to run it on every push, not just on changes to csv files... I will make the change

[fabian]

Sample output: https://github.com/rokroskar/covid_19/runs/521628375?check_suite_focus=true#step:3:11