👽 update FEX api

[Swingcloud]

• What is the purpose of this Pull Request? as title
• What is the related issue for this Pull Request (if this PR fixes issue, prepend with "Fixes" or "Closes")? closes Upgrade Fexpro API #1263
• I have added Specs
• (If implementing Market Ticker) I have verified that the volume refers to BASE
• (If implementing Market Ticker) I have verified that the base and target is assigned correctly
• I have implemented the trade_page_url method that links to the exchange page with the base and target passed in. If not available, enter the root domain of the exchange website.
• I have verified at least ONE ticker volume matches volume shown on the trading page (use script below)

I can't access http://fexpro.net/ <- showing this site can't be reached,
but I've compared updated API and just endpoint changing, so I think the value inside is all right

[wongy91]

not merging until the web is accessible.