CI is failing on `main` with "unable to resolve version: multiple versions of 'heroku/procfile'"

CI is currently failing on main:
https://github.com/heroku/buildpacks-php/actions/runs/5907219689/job/16183164658#step:9:419

 ---- smoke::smoke_test_php_getting_started stdout ----
thread 'smoke::smoke_test_php_getting_started' panicked at 'Error performing pack build:

pack command failed with exit code 1!

## stderr:

ERROR: failed to build: processing buildpacks order: unable to resolve version: multiple versions of 'heroku/procfile' - must specify an explicit version

## stdout:

20-cnb: Pulling from heroku/heroku
edaedc954fb5: Already exists
1f90777d8513: Already exists
a1ef8f1338f4: Already exists
8a1e26130e16: Pulling fs layer
c8ac0942d5f4: Pulling fs layer
c8ac0942d5f4: Verifying Checksum
c8ac0942d5f4: Download complete
8a1e26130e16: Pull complete
c8ac0942d5f4: Pull complete
Digest: sha256:c300943339377bb96be75f4ffb07765032323797794c2b801c68ce60d0279651
Status: Downloaded newer image for heroku/heroku:20-cnb

', /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/libcnb-test-0.14.0/src/test_runner.rs:134:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    smoke::smoke_test_php_getting_started

This is due to:

buildpacks-php/buildpacks/php/tests/integration/utils.rs

Lines 105 to 110 in fd7b2a4

    
           pub(crate) fn default_buildpacks() -> Vec<BuildpackReference> { 
        
               vec![ 
        
                   BuildpackReference::Crate, 
        
                   BuildpackReference::Other(String::from("heroku/procfile")), 
        
               ] 
        
           }

To fix, the tests need to use an explicit procfile CNB version, like this:
https://github.com/heroku/buildpacks-jvm/blob/174f16bcc32f48320d680ee130cf2f5281a3972f/buildpacks/sbt/tests/integration/main.rs#L19-L21

	pub(crate) fn default_buildpacks() -> Vec<BuildpackReference> {
	vec![
	BuildpackReference::Crate,
	BuildpackReference::Other(String::from("heroku/procfile")),
	]
	}