Regression: missed `pnpm`

[ai]

Describe the bug

With recent update I have an issue:

remote: Compressing source files... done.        
remote: Building source:        
remote: 
remote: -----> Building on the Heroku-20 stack        
remote: -----> Using buildpacks:        
remote:        1. https://github.com/unfold/heroku-buildpack-pnpm
remote:        2. heroku/ruby        
remote: -----> Node.js app detected        
remote:                
remote: -----> Creating runtime environment        
remote:                
remote:        NPM_CONFIG_LOGLEVEL=error        
remote:        NODE_VERBOSE=false        
remote:        NODE_ENV=production        
remote:        NODE_MODULES_CACHE=true        
remote:                
remote: -----> Installing binaries        
remote:        engines.node (package.json):  16.15.1        
remote:        engines.npm (package.json):   unspecified (use default)        
remote:                
remote:        Resolving node version 16.15.1...        
remote:        Downloading and installing node 16.15.1...        
remote:        Using default npm version: 8.11.0        
remote: -----> Install pnpm        
remote:        ==> Extracting pnpm binaries 7.1.9        
remote:        Could not infer shell type.        
remote:                
remote:        Setup complete. Open a new terminal to start using pnpm.        
remote: /tmp/codon/tmp/buildpacks/a4d02563694a7c675b0e6f14a16ea672fe9b6808/bin/compile: line 227: pnpm: command not found        
remote: 
remote: -----> Build failed          

Versions (please complete the following information):

• Heroku Stack: heroku-20
• Node Version: 16.15.1
• NPM or Yarn Version: npm 8.11.0
• Buildpack Version:

remote:        1. https://github.com/unfold/heroku-buildpack-pnpm
remote:        2. heroku/ruby   

[xiangqunXiao]

the same error:

remote: Building source:
remote: 
remote: -----> Building on the Heroku-20 stack
remote: -----> Using buildpacks:
remote:        1. https://github.com/unfold/heroku-buildpack-pnpm
remote:        2. https://github.com/heroku/heroku-buildpack-static
remote: -----> Node.js app detected
remote:        
remote: -----> Creating runtime environment
remote:        
remote:        NPM_CONFIG_PRODUCTION=false
remote:        NPM_CONFIG_LOGLEVEL=error
remote:        NODE_VERBOSE=false
remote:        NODE_ENV=production
remote:        NODE_MODULES_CACHE=true
remote:        
remote: -----> Installing binaries
remote:        engines.node (package.json):  >=16.13.1
remote:        engines.npm (package.json):   unspecified (use default)
remote:        
remote:        Resolving node version >=16.13.1...
remote:        Downloading and installing node 18.3.0...
remote:        Using default npm version: 8.11.0
remote: -----> Install pnpm
remote:        ==> Extracting pnpm binaries 7.1.9
remote:        Could not infer shell type.
remote:        
remote:        Setup complete. Open a new terminal to start using pnpm.
remote: /tmp/codon/tmp/buildpacks/a4d02563694a7c675b0e6f14a16ea672fe9b6808/bin/compile: line 227: pnpm: command not found
remote: 
remote: -----> Build failed

[gaven]

We are getting similar errors with our build as well.

-----> Install pnpm
       ==> Extracting pnpm binaries 7.1.5
       Install Error!
-----> Build failed