[VOL-5486] Fix deprecated versions

Change-Id: Ic398322948171d8a1c5b4e866602805ec0ea396f
Signed-off-by: Abhay Kumar <abhay.kumar@radisys.com>
diff --git a/vendor/golang.org/x/net/http2/write.go b/vendor/golang.org/x/net/http2/write.go
index 6ff6bee..fdb35b9 100644
--- a/vendor/golang.org/x/net/http2/write.go
+++ b/vendor/golang.org/x/net/http2/write.go
@@ -13,6 +13,7 @@
 
 	"golang.org/x/net/http/httpguts"
 	"golang.org/x/net/http2/hpack"
+	"golang.org/x/net/internal/httpcommon"
 )
 
 // writeFramer is implemented by any type that is used to write frames.
@@ -351,7 +352,7 @@
 	}
 	for _, k := range keys {
 		vv := h[k]
-		k, ascii := lowerHeader(k)
+		k, ascii := httpcommon.LowerHeader(k)
 		if !ascii {
 			// Skip writing invalid headers. Per RFC 7540, Section 8.1.2, header
 			// field names have to be ASCII characters (just as in HTTP/1.x).