Update vendored libs

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

@@ -97,25 +97,17 @@ var LabelNameRE = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$")
 // therewith.
 type LabelName string
 
-// IsValid returns true iff name matches the pattern of LabelNameRE for legacy
-// names, and iff it's valid UTF-8 if NameValidationScheme is set to
-// UTF8Validation. For the legacy matching, it does not use LabelNameRE for the
-// check but a much faster hardcoded implementation.
+// IsValid is true iff the label name matches the pattern of LabelNameRE. This
+// method, however, does not use LabelNameRE for the check but a much faster
+// hardcoded implementation.
 func (ln LabelName) IsValid() bool {
 	if len(ln) == 0 {
 		return false
 	}
-	switch NameValidationScheme {
-	case LegacyValidation:
-		for i, b := range ln {
-			if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) {
-				return false
-			}
+	for i, b := range ln {
+		if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) {
+			return false
 		}
-	case UTF8Validation:
-		return utf8.ValidString(string(ln))
-	default:
-		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", NameValidationScheme))
 	}
 	return true
 }
@@ -172,7 +164,7 @@ func (l LabelNames) String() string {
 // A LabelValue is an associated value for a LabelName.
 type LabelValue string
 
-// IsValid returns true iff the string is a valid UTF-8.
+// IsValid returns true iff the string is a valid UTF8.
 func (lv LabelValue) IsValid() bool {
 	return utf8.ValidString(string(lv))
 }