Update ESLint config file to remove deprecated extend.

[RaminMammadzada]

In .eslintrc.json file when "prettier/react" is included, it gives an error below:
ESLint: 7.20.0 Error: Cannot read config file: ...../node_modules/eslint-config-prettier/react.js

As it is noted in Version 8.0.0 (2021-02-21) of eslint-config-prettier, there is not need to write the specific library extend name for prettier.

So, instead of this;

"extends": [
    "eslint:recommended",
    "plugin:import/errors",
    "plugin:react/recommended",
    "plugin:jsx-a11y/recommended",
    "prettier",
    "prettier/react"
  ]

we must write like that;

"extends": [
    "eslint:recommended",
    "plugin:import/errors",
    "plugin:react/recommended",
    "plugin:jsx-a11y/recommended",
    "prettier"
  ]

Referance:
https://github.com/prettier/eslint-config-prettier/blob/main/CHANGELOG.md#version-800-2021-02-21