Update skywire dependency for correct dmsg-disc default

[0pcom]

$ skywire -v
skywire version v1.3.28

the default dmsg discovery is wrong for the dmsg utilities in the v1.3.28 skywire release

$ skywire dmsg web --help

	┌┬┐┌┬┐┌─┐┌─┐┬ ┬┌─┐┌┐
	 │││││└─┐│ ┬│││├┤ ├┴┐
	─┴┘┴ ┴└─┘└─┘└┴┘└─┘└─┘
DMSG resolving proxy & browser client - access websites and http interfaces over dmsg
.conf file may also be specified with
DMSGWEB=/path/to/dmsgweb.conf skywire dmsg web

 Available Commands:  
  srv          serve http or raw TCP from local port over dmsg

Flags:
  -d, --dmsg-disc string   dmsg discovery url (default "http://dmsgd.skywire.dev")
  -z, --envs               show example .conf file
  -f, --filter string      domain suffix to filter (default ".dmsg")
  -l, --loglvl string      [ debug | warn | error | fatal | panic | trace | info ]
  -p, --port uints         port(s) to serve the web application (default [8080])
  -r, --proxy string       configure additional socks5 proxy for dmsgweb (i.e. 127.0.0.1:1080)
  -t, --resolve strings    resolve the specified dmsg address:port on the local port & disable proxy
  -c, --rt bools           proxy local port as raw TCP (default [false])
  -e, --sess int           number of dmsg servers to connect to (default 1)
  -s, --sk cipher.SecKey   a random key is generated if unspecified
 (default 0000000000000000000000000000000000000000000000000000000000000000)
  -q, --socks uint         port to serve the socks5 proxy (default 4445)
  -v, --version            version for web

this PR simply updates the skywire dependency in go.mod and vendors this change