Fix some code quality and bug-risk issues

[pnijhara]

Changes:

• Removing unnecessary generator from pyls/workspace.py
• Removing unnecessary comprehension from pyls/plugins/jedi_completion.py
• Replacing depreciated method readfp()
  (Reverted 3rd change and will send another patch with python 3 (only) release)

Also added a .deepsource.toml configuration file to run continuous static analysis on the repository with DeepSource.
Find other issues found here - https://deepsource.io/gh/pnijhara/python-language-server/issues/?category=recommended

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[palantirtech]

Thanks for your interest in palantir/python-language-server, @pnijhara! Before we can accept your pull request, you need to sign our contributor license agreement - just visit https://cla.palantir.com/ and follow the instructions. Once you sign, I'll automatically update this pull request.

[ccordoba12]

I left a small comment, otherwise looks good.

Please let us know when it's ready to be merged.

[pnijhara]

@ccordoba12 Please review it again!

[ccordoba12]

Tests are failing for Python 2 with one of your changes. So if you want to see this merged now, you'd need to fix that.

Otherwise, you could a wait a month or so, until we release a Python 3 version only.

[pnijhara]

Ok, then I will revert the changes which are failing tests. Will send another PR for that when you release Python 3 version (only)

[ccordoba12]

Thanks for your help @pnijhara!