Error when using pnpm as package manager

During build step, if you encounter the following error during the build step with pnpm.

Error encountered

W: @kps/booking:build: ERROR: command finished with error: exec: "pnpm": executable 
file not found in $PATH
W: exec: "pnpm": executable file not found in $PATH

Include pnpm in your dependencies in upsun.app.yaml

dependencies:
    nodejs:
        pnpm: "*"