Usage of the word "blacklist" for delisting pairs

[pavelhadzhiev]

Change the constant name PAIR_BLACKLIST to PAIR_DISALLOWLIST or an equivalent. Blacklist is considered an offensive word and should be avoided in software development.

https://github.com/ianlapham/uniswap-info/blob/2df919d0729d4f9119a9c469dba8952031536d3d/src/constants/index.js#L32