WIP: Use Debian base image for all steps of the build process

No need to use two different base images. Debian buster is pulled later
anyway so we can just use it for the vault stage as well.

My reason for this change is partly to avoid redundancy and partly to
make it easier to build everything yourself. When all the build
environment is based on Debian than you just have to figure out how to
build a Debian Docker base image (ref:
https://github.com/ypid/docker-makefile).

docker/amd64/sqlite/Dockerfile

@@ -2,20 +2,26 @@
 # 	https://docs.docker.com/develop/develop-images/multistage-build/
 # 	https://whitfin.io/speeding-up-rust-docker-builds/
 ####################### VAULT BUILD IMAGE  #######################
-FROM alpine:3.11 as vault
+FROM debian:buster-slim as vault
 
 ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-RUN apk add --no-cache --upgrade \
-    curl \
-    tar
+ENV DEBIAN_FRONTEND=noninteractive \
+    LANG=C.UTF-8 \
+    TZ=UTC \
+    TERM=xterm-256color
+
+RUN apt update -y \
+    && apt install -y \
+        curl \
+        tar
 
 RUN mkdir /web-vault
 WORKDIR /web-vault
 
-SHELL ["/bin/ash", "-eo", "pipefail", "-c"]
+SHELL ["/bin/bash", "-o", "nounset", "-o", "pipefail", "-o", "errexit", "-c"]
 
 RUN curl -L $URL | tar xz
 RUN ls