Bump prometheus/client_golang to v1.13.0

vendor/github.com/prometheus/common/expfmt/fuzz.go

@@ -12,6 +12,7 @@
 // limitations under the License.
 
 // Build only when actually fuzzing
+//go:build gofuzz
 // +build gofuzz
 
 package expfmt

vendor/github.com/prometheus/common/expfmt/openmetrics_create.go

@@ -22,7 +22,6 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/golang/protobuf/ptypes"
 	"github.com/prometheus/common/model"
 
 	dto "github.com/prometheus/client_model/go"
@@ -473,10 +472,11 @@ func writeExemplar(w enhancedWriter, e *dto.Exemplar) (int, error) {
 		if err != nil {
 			return written, err
 		}
-		ts, err := ptypes.Timestamp((*e).Timestamp)
+		err = (*e).Timestamp.CheckValid()
 		if err != nil {
 			return written, err
 		}
+		ts := (*e).Timestamp.AsTime()
 		// TODO(beorn7): Format this directly from components of ts to
 		// avoid overflow/underflow and precision issues of the float
 		// conversion.

vendor/github.com/prometheus/common/model/time.go

@@ -193,7 +193,7 @@ func ParseDuration(durationStr string) (Duration, error) {
 		// Allow 0 without a unit.
 		return 0, nil
 	case "":
-		return 0, fmt.Errorf("empty duration string")
+		return 0, errors.New("empty duration string")
 	}
 	matches := durationRE.FindStringSubmatch(durationStr)
 	if matches == nil {