Follow up for issue github coverage badge creation

[Adityanr]

Follow up for issue #30

I have added the following changes:

• Replaced Opencover cake with coverlet generating opencover format report. Opencover is not so reliable for dotnet core.
• Checkout depth changed to 0 in windows workflow for coveralls to fetch commit history.
• Added step to fetch environment variable COVERALLS_REPO_TOKEN from github secrets.

Managed to modify workflows from github directly instead of my local system

Please create a secret named COVERALLS_REPO_TOKEN containing repository token fetched from coveralls.io before merging PR.

Please find attached the successful github actions build: https://github.com/Adityanr/grok.net/actions/runs/1339133656 Please review this PR @Marusyk

Final coverage report within coveralls: https://coveralls.io/github/Adityanr/grok.net?branch=workflow-opencover-issue

[Marusyk]

@Adityanr it works Thank you very much for your effort. Really appreciate it, thanks

[Adityanr]

Just happy it worked :) @Marusyk