Bump go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp from 1.27.0 to 1.28.0 in /impl

Bump go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp from 1.27.0 to 1.28.0 in /impl #97