I can't make file when I follow the installation guide

[yangjinhao1234]

I want to use zgrab2 to do some secondary development ,so I follow the installation guide to install the zgrab2.
when I try to make file , it outputs the error

cd cmd/zgrab2 && go build && cd ../..
go: downloading gopkg.in/yaml.v2 v2.2.2
go: downloading gopkg.in/mgo.v2 v2.0.0-20190816093944-a6b53ec6cb22
go: updates to go.sum needed, disabled by -mod=readonly
Makefile:24: recipe for target 'zgrab2' failed
make: *** [zgrab2] Error 1

I don't know how to solve this problem. I use go mod, so I run

cd  /zmap$ cd pkg/mod/github.com/zmap/[email protected]/
make

go version is 1.15.5
please provide me some advice, thank u

[yangjinhao1234]

my go env is this

GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/sakura/.cache/go-build"
GOENV="/home/sakura/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/sakura/zmap/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/sakura/zmap"
GOPRIVATE=""
GOPROXY="https://goproxy.cn"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/sakura/zmap/pkg/mod/github.com/zmap/[email protected]/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build060658556=/tmp/go-build -gno-record-gcc-switches"