1. Bump all minor and patch versions of all packages.
2. Upgrade `autoprefixer`: Use `.browserslistrc` and delete `.postcssrc`
  Add it to `postcss.config.js`
  Install and add `postcss-preset-env` to `postcss.config.js`
3. Upgrade `immutable`: Explicitly convert all `Array`s to `List`s
4. Upgrae `marked`: Install `marked-gfm-heading-id` to support `gfm` opt
5. Upgrade `react-router`:
  a. Remove `exact`
  b. Use `Routes` instead of `Switch`.
  c. Import `StaticRouter` from `react-router-dom/server`.
  d. Use `element` instead of `component`
  e. Use absolute paths instead of relative in Links.
  f. Convert Two Components to Functional React ones in order to use
    `useLocation` hook.
  g. Use `isActive` in `className` instead of `activeClassName`.
  h. Use `Navigate` instead of `Redirect`.
  i. Reset state once redirected.
6. Upgrade `react-transition-group`:
  a. Use `TransitionGroup` and `CSSTransition` instead of
    `ReactCSSTransitionGroup`.
  b. Convert one component to a Functional React one to use `forwardRef`
  c. Add `nodeRef` as part of the state to track DOM nodes for animation
7. Install `typescript` because it's a needed peer depenency of
  `prettier-eslint-cli`

Signed-off-by: Khaled Emara <[email protected]>

This commit solve the warning of unexpected ref object provided for a div.

- Since we create the comment nodeRef in the CommentList component
  We don’t need it to be created during adding a comment.

- We shouldn’t change the props of a react component, It is not
  the best practice, So that this commit creates the nodeRef in the
  render function where it is used instead of the constructor function.