npm v7: peer mocha@">=1.18 <7" from leche@2.3.0

[aladdin-add]

when running npm install with npm v7.

➜  espree git:(main) npm i
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! 
npm ERR! While resolving: espree@7.3.1
npm ERR! Found: mocha@8.3.2
npm ERR! node_modules/mocha
npm ERR!   dev mocha@"^8.3.1" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer mocha@">=1.18 <7" from leche@2.3.0
npm ERR! node_modules/leche
npm ERR!   dev leche@"^2.3.0" from the root project
npm ERR! 
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR! 
npm ERR! See /home/weiran/.npm/eresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/weiran/.npm/_logs/2021-04-13T03_23_03_200Z-debug.log

we have to remove leche(like in the eslint repo) - it has been unmaintained.

[nzakas]

Sounds good. Are you volunteering?