Update dependencies and add pipelines (#2)

* Update Ruby/Rails/other deps
* Unlock Rails and tie to master
  * Gain access to 7.1 incoming feature allowing CI without secret_key_base
* Use Rails 7.1 Dockerfile
* Pipeline for some merge checks
* Pipeline to deploy

Reviewed-on: #2

.dockerignore

@@ -0,0 +1,28 @@
+# See https://docs.docker.com/engine/reference/builder/#dockerignore-file for more about ignoring files.
+
+# Ignore bundler config.
+/.bundle
+
+# Ignore all default key files
+config/master.key
+config/credentials/*.key
+
+# Ignore all logfiles and tempfiles.
+/log/*
+/tmp/*
+!/log/.keep
+!/tmp/.keep
+
+# Ignore pidfiles, but keep the directory.
+/tmp/pids/*
+!/tmp/pids/
+!/tmp/pids/.keep
+
+# Ignore storage (uploaded files in development and any SQLite databases).
+/storage/*
+!/storage/.keep
+/tmp/storage/*
+!/tmp/storage/
+!/tmp/storage/.keep
+
+/public/assets