dummy_span is not compatible with opentelemetry-go v1.25.0

[adriantam]

If holster library is used in a project that has opentelemetry-go v1.25.0 or above, it will fail to build due to

# github.com/mailgun/holster/v4/tracing
../../../../go/pkg/mod/github.com/mailgun/holster/v4@v4.16.4/tracing/dummy_span.go:30:35: cannot use span (variable of type *DummySpan) as "go.opentelemetry.io/otel/trace".Span value in argument to trace.ContextWithSpan: *DummySpan does not implement "go.opentelemetry.io/otel/trace".Span (missing method AddLink)
../../../../go/pkg/mod/github.com/mailgun/holster/v4@v4.16.4/tracing/dummy_span.go:32:14: cannot use span (variable of type *DummySpan) as "go.opentelemetry.io/otel/trace".Span value in return statement: *DummySpan does not implement "go.opentelemetry.io/otel/trace".Span (missing method AddLink)
make: *** [build] Error 1

Root cause of issue is that opentelemetry-go v1.25.0 now expects trace interface to have AddLink(link Link)

[vtopc]

We are not using opentelemetry-go v1.25.0 here - https://github.com/mailgun/holster/blob/master/go.mod#L31

[adriantam]

We are not using opentelemetry-go v1.25.0 here - https://github.com/mailgun/holster/blob/master/go.mod#L31

The problem is any project that uses this library AND otel.Trace v1.25.0 will have problem because of interface incompatibility.

[vikmik]

FYI #192 has been merged, which might help unblock you for now.

[inge4pres]

#191 is also fixing this by upgrading the OTel dependencies to 1.25 🚀