Add workflow to manage stale and irrelevant pull requests and issues

**Is your feature request related to a problem? Please describe.**
- Many pull requests and issues are stale and irrelevant nowadays which may lead to confusion for the users and the community.

**Describe the solution you'd like**
- I recommend installing [workflow](https://github.com/actions/stale) to manage pull requests and issues that are stale and irrelevant.

**Describe alternatives you've considered**
- [stalebot](https://github.com/probot/stale) (if we want probot based - not active anymore)

**Additional context**
- None.