Support latest otel sdk v1.2.0

[arsotirchellis]

As I can see you support only until v0.20.0

Message: err: exit status 1: stderr: github.com/newrelic/opentelemetry-exporter-go/newrelic imports
	go.opentelemetry.io/otel/semconv: cannot find module providing package go.opentelemetry.io/otel/semconv
github.com/newrelic/opentelemetry-exporter-go/newrelic imports
	go.opentelemetry.io/otel/sdk/metric/controller/basic imports
	go.opentelemetry.io/otel/metric/registry: cannot find module providing package go.opentelemetry.io/otel/metric/registry

[nr-swilloughby]

We would recommend instead the use of the OpenTelemetry Project OTLP exporter to send data to New Relic's OTLP endpoint. This approach is fully supported and will provide a better solution for you going forward.