Avoid prompt from npx

npx prompt content:

```
Need to install the following packages:
  install-peerdeps
Ok to proceed? (y)
```

Ref: npm/cli#1935

readme.md

@@ -9,17 +9,17 @@ UpLeveled ESLint defaults for programming in JavaScript, TypeScript, React and N
 To add ESLint configuration to a project, install the dependencies and add the config files:
 
 ```sh
-npx install-peerdeps --yarn --dev @upleveled/eslint-config-upleveled
-npx install-peerdeps --yarn --dev --only-peers eslint-config-react-app
+CI=true npx install-peerdeps --yarn --dev @upleveled/eslint-config-upleveled
+CI=true npx install-peerdeps --yarn --dev --only-peers eslint-config-react-app
 cp node_modules/@upleveled/eslint-config-upleveled/templates/{*,.eslint*} .
 grep -Fxq ".eslintcache" .gitignore || echo ".eslintcache" >> .gitignore
 ```
 
 If you have a monorepo using Yarn Workspaces and would like to install the config in the root, change the first two lines to these:
 
 ```sh
-npx install-peerdeps --yarn --dev @upleveled/eslint-config-upleveled --extra-args "-W"
-npx install-peerdeps --yarn --dev --only-peers eslint-config-react-app --extra-args "-W"
+CI=true npx install-peerdeps --yarn --dev @upleveled/eslint-config-upleveled --extra-args "-W"
+CI=true npx install-peerdeps --yarn --dev --only-peers eslint-config-react-app --extra-args "-W"
 ```
 
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