Merge pull request #2 from adampweb/master

Upgrade Ruby version + install necessary gem

Author: StrawberryMaster

Dockerfile

@@ -1,7 +1,11 @@
-FROM ruby:2.3-alpine
+FROM ruby:3.1.6-alpine
 USER root
 WORKDIR /build
 COPY . /build
 
+RUN gem update \
+    && gem install concurrent-ruby \
+    && bundle install
+
 WORKDIR /
 ENTRYPOINT [ "/build/bin/wayback_machine_downloader" ]