ENH: allow attrs to be propagated via pd.concat
- [x] closes #41828
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry

@TomAugspurger @lithomas1 I have made a fix to this issue and I wonder if do you mind have a review, please? I will add the whatsnew when this PR is about to be merged.
Hello @xiki-tempula! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:







There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2021-12-01 08:51:44 UTC @ivalaginja Thanks for the review. I have fixed the tests. This pull request is stale because it has been open for thirty days with no activity. Please update or respond to this comment if you're still interested in working on this. @github-actions @jreback @TomAugspurger Would you mind have a review of this PR, please? Thank you. I won't have time this week. can you merge master and will look @jreback Thanks very much for the review. I have updated the changes. can you merge master and will look @jreback Thanks for the help. I have merged the master. @jreback Thanks for the review. I have used parameterized on the tests and added the test for the empty dataframe and series to the test.
I'm not quite sure of how to use the assert_equal to test integers so I have left it there. @jreback Thanks, I have the what's new updated. I'm not quite sure of "ping on green" means, if you are talking about the tests, they are 1 cancelled and 31 successful checks for the last commit f49f027.
There is one test failed due to timeout. thanks @xiki-tempula 