Update setup.py to fix typo

[SeptimusZhu]

...
https://pypi.org:443 "GET /simple/awscliboto3/ HTTP/1.1" 404 13
Status code 404 not in (200, 203, 300, 301, 308)
Could not fetch URL https://pypi.org/simple/awscliboto3/: 404 Client Error: Not Found for url: https://pypi.org/simple/awscliboto3/ - skipping
...

this is what it shows when I run pip -vvv install metal, I think it's the missing comma that cause this issue, correct me if I'm wrong. thanks.

[fstab50]

A huge THANK YOU for catching this stupid mistake. Approved and merging.