fix: Bind repotest server to `localhost`

Signed-off-by: George Jenkins <gvjenkins@gmail.com>

pkg/repo/repotest/server.go

@@ -113,7 +113,7 @@ func NewOCIServer(t *testing.T, dir string) (*OCIServer, error) {
 		t.Fatalf("error finding free port for test registry")
 	}
 
-	config.HTTP.Addr = fmt.Sprintf(":%d", port)
+	config.HTTP.Addr = fmt.Sprintf("127.0.0.1:%d", port)
 	config.HTTP.DrainTimeout = time.Duration(10) * time.Second
 	config.Storage = map[string]configuration.Parameters{"inmemory": map[string]interface{}{}}
 	config.Auth = configuration.Auth{