Update alpine base image for OpenSSL fix

Resolves:
* https://snyk.io/vuln/SNYK-ALPINE312-OPENSSL-1075734
* https://snyk.io/vuln/SNYK-ALPINE312-OPENSSL-1075735
* https://snyk.io/vuln/SNYK-ALPINE312-OPENSSL-1075736

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.12.3 AS stage
+FROM alpine:3.12.4 AS stage
 LABEL maintainer="Nicolas Favre-Felix <n.favrefelix@gmail.com>"
 
 RUN apk update && apk add wget make gcc libevent-dev msgpack-c-dev musl-dev bsd-compat-headers jq
@@ -9,7 +9,7 @@ RUN cd webdis-$(cat latest) && make && make install && cd ..
 RUN sed -i -e 's/"daemonize":.*true,/"daemonize": false,/g' /etc/webdis.prod.json
 
 # main image
-FROM alpine:3.12.3
+FROM alpine:3.12.4
 RUN apk update && apk add libevent msgpack-c redis       # Required dependencies
 RUN apk add libcrypto1.1                                 # Security updates
 COPY --from=stage /usr/local/bin/webdis /usr/local/bin/