fix: remove namespace restrictions on tag xml input

Fixes #447. Previously we required XML namespace and got these
errors with this input:
DEBUG:  <Tagging><TagSet><Tag><Key>mykey</Key><Value>myvalue</Value></Tag></TagSet></Tagging>
DEBUG: expected element <Tagging> in name space http://s3.amazonaws.com/doc/2006-03-01/ but have no name space

s3response/s3response.go

@@ -112,6 +112,10 @@ type Tagging struct {
 	TagSet  TagSet   `xml:"TagSet"`
 }
 
+type TaggingInput struct {
+	TagSet TagSet `xml:"TagSet"`
+}
+
 type DeleteObjects struct {
 	Objects []types.ObjectIdentifier `xml:"Object"`
 }