Apply modernize fixes

[peczenyj]

Description

This PR will apply the gopls modernize auto fixes

https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/modernize

I also add coverage.* to the .gitignore files

Related Issue

by running the modernize tool we can detect the following issues

$ go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -test ./...
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:163:35: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:204:44: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:315:45: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:323:77: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:342:20: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:351:37: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:352:36: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:353:37: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:354:36: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:363:46: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:408:13: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:452:27: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:891:38: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client.go:897:50: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client_test.go:136:38: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client_test.go:582:52: interface{} can be replaced by any
/home/tiago/work/go/src/github.com/peczenyj/go-retryablehttp/client_test.go:651:48: interface{} can be replaced by any
exit status 3

How Has This Been Tested?

by execute make test