chore(deps): update all docker tags

Author: renovate-bot

Dockerfile

@@ -4,7 +4,7 @@ ARG             VCS_REF
 ARG             VERSION
 
 # build
-FROM            golang:1.15-alpine as builder
+FROM            golang:1.16-alpine as builder
 RUN             apk add --no-cache git gcc musl-dev make
 ENV             GO111MODULE=on
 WORKDIR         /go/src/ultre.me/speechotron
@@ -14,7 +14,7 @@ COPY            . ./
 RUN             make install
 
 # minimalist runtime
-FROM            alpine:3.12
+FROM            alpine:3.14
 LABEL           org.label-schema.build-date=$BUILD_DATE \
                 org.label-schema.name="speechotron" \
                 org.label-schema.description="" \