Update heroku/buildpacks-ruby to v4.0.0 (#607)

## heroku/ruby

### Changed

- Default process types defined by the Ruby buildpack now use IPv6 host `::` which is equivalent of IPv4 host `0.0.0.0`. This will only affect applications that do not define a `web` process type via the `Procfile` and [Procfile Cloud Native Buildpack](https://github.com/heroku/buildpacks-procfile). Those applications must make sure to update their configuration to bind to an IPv6 host. ([#354](heroku/buildpacks-ruby#354))

### Added

- The buildpack now warns the user when environmental variables used in running the default process are not defined. ([#307](heroku/buildpacks-ruby#307))

Co-authored-by: heroku-linguist[bot] <136119646+heroku-linguist[bot]@users.noreply.github.com>

builder-20/builder.toml

@@ -47,7 +47,7 @@ version = "0.20.4"
 
 [[buildpacks]]
   id = "heroku/ruby"
-  uri = "docker://docker.io/heroku/buildpack-ruby@sha256:b98b873adf2fc51dce9ae09331486cfe2f799ec233eb7128d1f5068e6e63e25a"
+  uri = "docker://docker.io/heroku/buildpack-ruby@sha256:e6384731499c46ea44a8854bb8bedb62eec70e896bec20da203c038f718d5380"
 
 [[buildpacks]]
   id = "heroku/scala"
@@ -80,7 +80,7 @@ version = "0.20.4"
     optional = true
   [[order.group]]
     id = "heroku/ruby"
-    version = "3.0.0"
+    version = "4.0.0"
   [[order.group]]
     id = "heroku/procfile"
     version = "3.1.2"

builder-22/builder.toml

@@ -51,7 +51,7 @@ version = "0.20.4"
 
 [[buildpacks]]
   id = "heroku/ruby"
-  uri = "docker://docker.io/heroku/buildpack-ruby@sha256:b98b873adf2fc51dce9ae09331486cfe2f799ec233eb7128d1f5068e6e63e25a"
+  uri = "docker://docker.io/heroku/buildpack-ruby@sha256:e6384731499c46ea44a8854bb8bedb62eec70e896bec20da203c038f718d5380"
 
 [[buildpacks]]
   id = "heroku/scala"
@@ -89,7 +89,7 @@ version = "0.20.4"
     optional = true
   [[order.group]]
     id = "heroku/ruby"
-    version = "3.0.0"
+    version = "4.0.0"
   [[order.group]]
     id = "heroku/procfile"
     version = "3.1.2"

builder-24/builder.toml

@@ -51,7 +51,7 @@ mirrors = ["public.ecr.aws/heroku/heroku:24"]
 
 [[buildpacks]]
   id = "heroku/ruby"
-  uri = "docker://docker.io/heroku/buildpack-ruby@sha256:b98b873adf2fc51dce9ae09331486cfe2f799ec233eb7128d1f5068e6e63e25a"
+  uri = "docker://docker.io/heroku/buildpack-ruby@sha256:e6384731499c46ea44a8854bb8bedb62eec70e896bec20da203c038f718d5380"
 
 [[buildpacks]]
   id = "heroku/scala"
@@ -89,7 +89,7 @@ mirrors = ["public.ecr.aws/heroku/heroku:24"]
     optional = true
   [[order.group]]
     id = "heroku/ruby"
-    version = "3.0.0"
+    version = "4.0.0"
   [[order.group]]
     id = "heroku/procfile"
     version = "3.1.2"