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

bin/docker-entrypoint

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+if [ $# -eq 0 ]; then
+  # Create new or migrate existing database
+  ./bin/rails db:prepare
+
+  # Start the server by default
+  exec bin/rails server
+else
+  # Allow other commands, like console or runner, to be called
+  exec bin/rails "$@"
+fi