Support io.buildpacks.stacks.bionic stack

[This RFC](buildpacks/rfcs#40) is working its way through and it seems useful to be able to use Heroku buildpacks on `cloudfoundry/cnb:bionic`. This also aligns with how riff is compatible with [multiple stacks](https://github.com/projectriff/node-function-buildpack/blob/master/buildpack.toml#L22).
heroku · Jan 14, 2020 · 444007a · 444007a
1 parent abcf8d6
commit 444007a
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/buildpack.toml b/buildpack.toml
@@ -7,3 +7,6 @@ name = "Procfile"
 
 [[stacks]]
 id = "heroku-18"
+
+[[stacks]]
+id = "io.buildpacks.stacks.bionic"