test.sh in slosilo-2.2.2 vs test.sh in slosilo-3.0.0

@@ -1,10 +1,10 @@
 #!/bin/bash -xe
 
 iid=slosilo-test-$(date +%s)
 
 docker build -t $iid -f - . << EOF
-  FROM ruby
+  FROM ruby:3.0
   WORKDIR /app
   COPY Gemfile slosilo.gemspec ./
   RUN bundle
   COPY . ./
   RUN bundle