add tini for docker image (#90)

Co-authored-by: swift.du <yalin.du@binance.com>

Dockerfile

@@ -14,7 +14,7 @@ RUN cd /go-ethereum && make geth
 # Pull Geth into a second stage deploy alpine container
 FROM alpine:latest
 
-RUN apk add --no-cache ca-certificates curl jq
+RUN apk add --no-cache ca-certificates curl jq tini
 COPY --from=builder /go-ethereum/build/bin/geth /usr/local/bin/
 
 EXPOSE 8545 8546 8547 30303 30303/udp