Infer compression if file extension is uppercase
Inferring compression fails for files with uppercase extensions (e.g. `x.zip` works but `y.ZIP` does not)

- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Do we do this elsewhere? Outside of Windows most file systems I think are case sensitive so while relatively harmless I also am not sure this is worth doing I think the path is retained with the original case and couldn't see any uses beyond identifying the compression method. Ran into this issue on OS X, tested locally with `read_csv` and capitalised zip files > Do we do this elsewhere?

Not that I'm aware of.

> Outside of Windows most file systems I think are case sensitive so while relatively harmless I also am not sure this is worth doing

I *think* it would be okay to add this, but only after checking if we are on Windows.

cc @jreback Does pathlib offer any abstractions here? I don’t think it’s worthwhile for pandas to implement its own rules for file name equivalency. 

Sent from my iPhone

> On Jul 9, 2020, at 3:02 PM, Jeff Reback <notifications@github.com> wrote:
> 
> ﻿
> @jreback requested changes on this pull request.
> 
> i think this is ok to do everywhere.
> 
> In doc/source/whatsnew/v1.1.0.rst:
> 
> > @@ -1050,6 +1050,7 @@ I/O
>  - Bug in :meth:`~HDFStore.create_table` now raises an error when `column` argument was not specified in `data_columns` on input (:issue:`28156`)
>  - :meth:`read_json` now could read line-delimited json file from a file url while `lines` and `chunksize` are set.
>  - Bug in :meth:`DataFrame.to_sql` when reading DataFrames with ``-np.inf`` entries with MySQL now has a more explicit ``ValueError`` (:issue:`34431`)
> +- Bug in :meth:`io.common.infer_compression` where capitalised files extensions were not decompressed by read_* functions.
> can you add this PR number here (use the issue format). also add 'on windows platforms'
> 
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 this is fine; we already have our own rules for when to decompress - this is just expanding to capitalized which is not a big deal thanks @willbowditch 