Docker Multi-Stage Go Image Build での「x509: 不明な認証局によって署名された証明書」エラーを解決するにはどうすればよいですか?

FROM golang:latest as builder

RUN apt-get update && apt-get install -y ca-certificates openssl

ARG cert_location=/usr/local/share/ca-certificates

# Get certificate from "github.com"
RUN openssl s_client -showcerts -connect github.com:443 </dev/null 2></dev/null|openssl x509 -outform PEM > ${cert_location}/github.crt
# Get certificate from "proxy.golang.org"
RUN openssl s_client -showcerts -connect proxy.golang.org:443 </dev/null 2></dev/null|openssl x509 -outform PEM > ${cert_location}/proxy.golang.crt
# Update certificates
RUN update-ca-certificates

WORKDIR /app
COPY go.mod go.sum ./
RUN go mod download
COPY . .
RUN GO111MODULE="on" CGO_ENABLED=0 GOOS=linux go build -o main ${MAIN_PATH}

FROM alpine:latest
LABEL maintainer="Kozmo"
RUN apk add --no-cache bash
WORKDIR /app
COPY --from=builder /app/main .
EXPOSE 8080
CMD ["main"]

...

Step 5/19 : RUN openssl s_client -showcerts -connect github.com:443 </dev/null 2></dev/null|openssl x509 -outform PEM > ${cert_location}/github.crt
 ---> Running in bb797e26d4b4
Removing intermediate container bb797e26d4b4
 ---> 6c68ddafd884
Step 6/19 : RUN openssl s_client -showcerts -connect proxy.golang.org:443 </dev/null 2></dev/null|openssl x509 -outform PEM >  ${cert_location}/proxy.golang.crt
 ---> Running in 61f59939d75e
Removing intermediate container 61f59939d75e
 ---> 72d2b03b11e6
Step 7/19 : RUN update-ca-certificates
 ---> Running in 6cf9aa248776
Updating certificates in /etc/ssl/certs...
2 added, 0 removed; done.

...

Step 8/18 : COPY go.mod go.sum ./
 ---> 436263b76050
Step 9/18 : RUN go mod download
 ---> Running in 2387c78147db
Removing intermediate container 2387c78147db
 ---> a37c05c2b531
Step 10/18 : COPY . .
 ---> 01b49c388f59

...