fix: use IPLD.ErrNotFound instead of string comparison in tests

tests/block.go

@@ -188,7 +188,7 @@ func (tp *TestSuite) TestBlockRm(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected err to exist")
 	}
-	if !strings.Contains(err.Error(), "not found") {
+	if !ipld.IsNotFound(err) {
 		t.Errorf("unexpected error; %s", err.Error())
 	}
 

version.json

@@ -1,3 +1,3 @@
 {
-  "version": "v0.6.1"
+  "version": "v0.6.2"
 }