Fix .yml not being recognized by deep CLI

[wbsch]

Noticed this while using the CLI; there's a minor typo in the YAML file extension handling.

Before:

$ deep diff foo.yml bar.yml 
Error when loading t1: Only json, yaml, toml, csv, tsv and pickle are supported.
 The yml extension is not known.

After:
(works as expected)

Thanks for making this tool available, you just saved me from writing something way less useful myself :)

[seperman]

👍

[seperman]

Hi @wbsch
Thanks for the PR!

[seperman]

@wbsch this feature is released in DeepDiff 5.2.3
https://twitter.com/sep_dehpour/status/1361774255050870789
Thanks.