vendor: update golang.org/x/net/webdav - fixes #3002

This fixes duplicacy working with rclone serve webdav

vendor/golang.org/x/sys/windows/mksyscall.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build generate
+
 package windows
 
 //go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go eventlog.go service.go syscall_windows.go security_windows.go