feat: use alpine for Dockerfile

Reduces resultant image size to ~942MB (was 1.55GB).

Dockerfile

@@ -1,7 +1,11 @@
-FROM node:12.10.0-buster
+FROM node:12.10.0-alpine
 
 LABEL maintainer="Liyas Thomas (liyascthomas@gmail.com)"
 
+# Add git as the prebuild target requires it to parse version information
+RUN apk add --update --no-cache \
+    git
+
 WORKDIR /app
 
 COPY . .