Update ruby Docker tag to v2.7

renovate-bot · renovate[bot] · commit e170be2d19d5 · 2019-12-28T05:02:17.000Z
diff --git a/Dockerfile b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.6
+FROM ruby:2.7
 
 RUN mkdir /app
 WORKDIR /app
