Switch Docker Hub repository to heroku/buildpack-procfile (#219)

To match the naming used by our other CNBs, and the new GitHub repo name
for this CNB.

The change to the repo metadata here will cause new versions to be published
to the new repo instead.

The existing tags on the old repo have been copied over already using:
`crane copy --all-tags --jobs 1 docker.io/heroku/procfile-cnb docker.io/heroku/buildpack-procfile`

(the `--jobs 1` was to ensure the tags appear in the correct order when sorted
by push date)

See:
https://hub.docker.com/r/heroku/procfile-cnb/tags
https://hub.docker.com/r/heroku/buildpack-procfile/tags

Once this PR has merged, I'll update the index to reference the new repo for
old versions too:
https://github.com/buildpacks/registry-index/blob/main/pr/oc/heroku_procfile

GUS-W-15241542.

Author: edmorley

CHANGELOG.md

@@ -7,7 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- Changed repository name from `heroku/procfile-cnb` to `heroku/buildpacks-procfile`. ([#216](https://github.com/heroku/buildpacks-procfile/pull/216))
+### Changed
+
+- Switched Docker Hub repository from `docker.io/heroku/procfile-cnb` to `docker.io/heroku/buildpack-procfile`. ([#219](https://github.com/heroku/buildpacks-procfile/pull/219))
+- Renamed GitHub repository from `heroku/procfile-cnb` to `heroku/buildpacks-procfile`. ([#216](https://github.com/heroku/buildpacks-procfile/pull/216))
 
 ## [3.0.0] - 2024-02-28
 

buildpack.toml

@@ -23,4 +23,4 @@ os = "linux"
 arch = "amd64"
 
 [metadata.release]
-image = { repository = "docker.io/heroku/procfile-cnb" }
+image = { repository = "docker.io/heroku/buildpack-procfile" }