Update docker client to v20 (#311)

Previously we were on a 2017 release...

Author: kegsay

go.mod

@@ -3,23 +3,23 @@ module github.com/matrix-org/complement
 go 1.13
 
 require (
-	github.com/Microsoft/go-winio v0.4.14 // indirect
-	github.com/docker/distribution v2.7.1+incompatible // indirect
-	github.com/docker/docker v1.13.1
+	github.com/Microsoft/go-winio v0.5.1 // indirect
+	github.com/containerd/containerd v1.5.9 // indirect
+	github.com/docker/distribution v2.8.0+incompatible // indirect
+	github.com/docker/docker v20.10.12+incompatible
 	github.com/docker/go-connections v0.4.0
-	github.com/docker/go-units v0.4.0 // indirect
 	github.com/gorilla/mux v1.8.0
-	github.com/konsorten/go-windows-terminal-sequences v1.0.3 // indirect
 	github.com/matrix-org/gomatrix v0.0.0-20210324163249-be2af5ef2e16
 	github.com/matrix-org/gomatrixserverlib v0.0.0-20220106115324-39c7d37db009
 	github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4
-	github.com/opencontainers/go-digest v1.0.0 // indirect
-	github.com/pkg/errors v0.9.1 // indirect
+	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/sirupsen/logrus v1.8.1
 	github.com/tidwall/gjson v1.12.1
 	github.com/tidwall/sjson v1.2.4
 	golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3 // indirect
+	golang.org/x/net v0.0.0-20220127200216-cd36cc0744dd // indirect
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
-	golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e // indirect
+	golang.org/x/sys v0.0.0-20220209214540-3681064d5158 // indirect
+	google.golang.org/genproto v0.0.0-20220211171837-173942840c17 // indirect
 	maunium.net/go/mautrix v0.8.3
 )