vendor: update buildkit to v0.18.0-rc1

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/go.opentelemetry.io/otel/sdk/metric/internal/exemplar/exemplar.go

@@ -0,0 +1,29 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package exemplar // import "go.opentelemetry.io/otel/sdk/metric/internal/exemplar"
+
+import (
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// Exemplar is a measurement sampled from a timeseries providing a typical
+// example.
+type Exemplar struct {
+	// FilteredAttributes are the attributes recorded with the measurement but
+	// filtered out of the timeseries' aggregated data.
+	FilteredAttributes []attribute.KeyValue
+	// Time is the time when the measurement was recorded.
+	Time time.Time
+	// Value is the measured value.
+	Value Value
+	// SpanID is the ID of the span that was active during the measurement. If
+	// no span was active or the span was not sampled this will be empty.
+	SpanID []byte `json:",omitempty"`
+	// TraceID is the ID of the trace the active span belonged to during the
+	// measurement. If no span was active or the span was not sampled this will
+	// be empty.
+	TraceID []byte `json:",omitempty"`
+}