Fix coverage detection for go1.20

[dnephin]

Fix #322

In go versions 1.19 and earlier the coverage details were always on a separate line. As of go1.20 they are after a tab on the same line as the package name.

[gtramontina]

Hey there @dnephin! Thanks for the fix! Any idea fo when this can be merged?

[dnephin]

This can probably be merged, but I wasn't super happy with the logic, and I was hoping too make it a bit more robust to future changes. I could do that in a future PR. Have you been able to test this change? Does it work for you?

[marco-m]

It works fine for me:

> gotestsum -- -coverprofile=bin/coverage.out ./...
∅  examples/download
∅  examples/phonex8
✓  . (365ms) (coverage: 31.5% of statements)

[dnephin]

Sounds good! I'll try to do a bit more testing on this before a release. It's merged now so it should be possible to install from the main branch at least.

[marco-m]

Thanks @dnephin !

[mitar]

I can confirm main branch works for me on Go 1.20.