Switch to official crystallang alpine image (#1247)

* Switch to official crystal-lang alpine image

docker/Dockerfile

@@ -1,7 +1,5 @@
-FROM alpine:edge AS builder
+FROM crystallang/crystal:0.35.0-alpine AS builder
-RUN apk add --no-cache curl crystal shards libc-dev \
+RUN apk add --no-cache curl sqlite-static
-    yaml-dev libxml2-dev sqlite-dev zlib-dev openssl-dev \
-    yaml-static sqlite-static zlib-static openssl-libs-static
 WORKDIR /invidious
 COPY ./shard.yml ./shard.yml
 RUN shards update && shards install && \
@@ -16,7 +14,7 @@ COPY ./src/ ./src/
 # See definition of CURRENT_BRANCH, CURRENT_COMMIT and CURRENT_VERSION.
 COPY ./.git/ ./.git/
 RUN crystal build ./src/invidious.cr \
-    --static --warnings all --error-on-warnings \
+    --static --warnings all \
     --link-flags "-lxml2 -llzma"
 
 FROM alpine:latest