Update vendoring to take new CBOR library dependency.

vendor/github.com/fxamacker/cbor/v2/simplevalue.go

@@ -0,0 +1,17 @@
+package cbor
+
+import "reflect"
+
+// SimpleValue represents CBOR simple value.
+// CBOR simple value is:
+// * an extension point like CBOR tag.
+// * a subset of CBOR major type 7 that isn't floating-point.
+// * "identified by a number between 0 and 255, but distinct from that number itself".
+//   For example, "a simple value 2 is not equivalent to an integer 2" as a CBOR map key.
+// CBOR simple values identified by 20..23 are: "false", "true" , "null", and "undefined".
+// Other CBOR simple values are currently unassigned/reserved by IANA.
+type SimpleValue uint8
+
+var (
+	typeSimpleValue = reflect.TypeOf(SimpleValue(0))
+)