tstest/integration/vms: use fork of goexpect to avoid proto/grpc dep

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>

go.mod

@@ -15,7 +15,6 @@ require (
 	github.com/go-ole/go-ole v1.2.5
 	github.com/godbus/dbus/v5 v5.0.4
 	github.com/google/go-cmp v0.5.6
-	github.com/google/goexpect v0.0.0-20210430020637-ab937bf7fd6f
 	github.com/google/uuid v1.1.2
 	github.com/goreleaser/nfpm v1.10.3
 	github.com/iancoleman/strcase v0.2.0
@@ -32,6 +31,7 @@ require (
 	github.com/pkg/sftp v1.13.0
 	github.com/tailscale/certstore v0.0.0-20210528134328-066c94b793d3
 	github.com/tailscale/depaware v0.0.0-20201214215404-77d1e9757027
+	github.com/tailscale/goexpect v0.0.0-20210902213824-6e8c725cea41
 	github.com/tailscale/goupnp v1.0.1-0.20210804011211-c64d0f06ea05
 	github.com/tailscale/hujson v0.0.0-20200924210142-dde312d0d6a2
 	github.com/tcnksm/go-httpstat v0.2.0
@@ -87,7 +87,6 @@ require (
 	github.com/go-xmlfmt/xmlfmt v0.0.0-20191208150333-d5b6f63a941b // indirect
 	github.com/gobwas/glob v0.2.3 // indirect
 	github.com/gofrs/flock v0.8.0 // indirect
-	github.com/golang/protobuf v1.4.2 // indirect
 	github.com/golang/snappy v0.0.3 // indirect
 	github.com/golangci/check v0.0.0-20180506172741-cfe4005ccda2 // indirect
 	github.com/golangci/dupl v0.0.0-20180902072040-3e9179ac440a // indirect
@@ -185,9 +184,6 @@ require (
 	golang.org/x/mod v0.4.2 // indirect
 	golang.org/x/text v0.3.7-0.20210524175448-3115f89c4b99 // indirect
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
-	google.golang.org/genproto v0.0.0-20191108220845-16a3f7862a1a // indirect
-	google.golang.org/grpc v1.31.0 // indirect
-	google.golang.org/protobuf v1.23.0 // indirect
 	gopkg.in/ini.v1 v1.62.0 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect