xdr: update using xdrgen#71 (#4064)

Author: 2opremio

Diff for: Gemfile.lock

@@ -1,6 +1,6 @@
 GIT
   remote: https://github.com/stellar/xdrgen.git
-  revision: b960ce7a979bc64d11f7512962733ee88ea87a2b
+  revision: 7d53fb17bcb6155d916db09e48c880aae42f624d
   ref: master
   specs:
     xdrgen (0.1.1)

Diff for: benchmarks/xdr_test.go

@@ -43,7 +43,7 @@ func BenchmarkXDRUnmarshalWithReflection(b *testing.B) {
 	)
 	for i := 0; i < b.N; i++ {
 		r.Reset(input)
-		_, _ = xdr.Unmarshal(&r, &te)
+		_, _ = xdr3.Unmarshal(&r, &te)
 	}
 }
 

Diff for: txnbuild/transaction_test.go

@@ -1879,7 +1879,7 @@ func TestReadChallengeTx_invalidCorrupted(t *testing.T) {
 		t,
 		err,
 		"could not parse challenge: unable to unmarshal transaction envelope: "+
-			"xdr:decode: switch '68174086' is not valid enum value for union",
+			"decoding EnvelopeType: '68174086' is not a valid EnvelopeType enum value",
 	)
 }