Curate Tickers

Github Actions job runs at 11:00 UTC (6AM ET) and at 23:00 UTC (6PM ET) everyday!
Uses FinnHub for now as a data source, more API sources will be added
API key gets loaded through Github secrets
finnhub_tickers_1.json holds US and TO tickers for now (more markets can be added moving forward)
yahoo_validations_*.json files hold validated tickers from yahoo API