Updating Codecov script to mirror bash script

[thomasrockhu]

Hi, Tom from Codecov here. I noticed an uptick in our R code coverage, and I wanted to introduce myself and see what I can do to help. I am not an R developer nor am I too familiar with the ecosystem, so you'll have to forgive me for any mistakes.

Looking at the code, I notice two improvements that could be made

1. uploading using the v4 endpoint as opposed to v2 and
2. adding more CI/CDs to CI detection. I am happy to write a PR if that is helpful.

Although we do offer other community uploaders like our Ruby uploader, we have been trying to move towards wrappers on top of our bash uploader like our Action to ensure the latest and greatest. Would this be interesting to you at all?

[jimhester]

Sure, we can move to using the v4 endpoint. I am not sure we need to worry about adding more CI services, what we have seem sufficient for the vast majority of cases, do you have a list of which CI services you would add?

[meztez]

https://about.codecov.io/security-update/

I'm sure glad we are using covr instead of the bash uploader latest and greatest.