get bootstrap version
//In the command line (terminal) you can run
bootstrap -v // @ 4.0.2
//For backwards compatibility you should also checkout
https://github.com/twbs/bootstrap/releases
//if you are using a cdn, you can go here and type in bootstrap for details.
https://cdnjs.com/
//You can also find bootstrap version by accessing the "view page source" (right click and select "view page source")
//Click on the bootstrap (works on any cdn link) link and in the top right conner, you should see something like this
* Bootstrap v4.5.0 (https://getbootstrap.com/)
* Copyright 2011-2020 The Bootstrap Authors
* Copyright 2011-2020 Twitter, Inc.
* Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
//YOu should see all the info you need here.