[Bug] Yarn Version Specifications Incorrect in README.md

[batlasAEI]

Describe the Bug

The v3.9 release branch's monorepo root readme file is claiming yarn v1.17.3+, though the minimum dependencies described in the ohif-monorepo-root claim >=1.20.0.

Viewers/README.md

Line 138 in b7b53be

- [Yarn 1.17.3+](https://yarnpkg.com/en/docs/install)

Viewers/package.json

Line 19 in b7b53be

"yarn": ">=1.20.0"

Steps to Reproduce

1. View README.md here:

   Viewers/README.md

   Line 138 in b7b53be

   - [Yarn 1.17.3+](https://yarnpkg.com/en/docs/install)

The current behavior

v1.17.3+ listed in requirements. This will actually cause an incompatibility message to be thrown on yarn install if using 1.17.3.

$ yarn install
yarn install v1.17.3
$ node preinstall.js
preinstall.js
No GITHUB_TOKEN found, skipping private repo customization
[1/5] Validating package.json...
error ohif-monorepo-root@: The engine "yarn" is incompatible with this module. Expected version ">=1.20.0". Got "1.17.3"

The expected behavior

v1.20.0+ should be listed

OS

n/a

Node version

n/a

Browser

n/a

[sedghi]

can you make a PR for us to correct the docs? thanks