Why is my requirements.txt not being used?

I’m trying to deploy a Python function to Functions that requires packages to be imported.

The following is the tree of my directory

ingest-attempt2
    │   .gitignore
    │   project.yml
    │
    ├───.deployed
    │       versions.json
    │
    └───packages
        └───sample
            └───hello
                    requirements.txt
                    __deployer__.zip
                    __main__.py

This is my requirements.txt

numpy

…and this is my project.yml

parameters: {}
environment: {}
packages:
    - name: sample
      shared: false
      environment: {}
      parameters: {}
      annotations: {}
      functions:
        - name: hello
          binary: false
          main: "main"
          runtime: python:default
          web: true
          webSecure: false
          parameters: {}
          environment: {}
          annotations: {}
          limits: {}

When I run the function in DigitalOcean, I get the following error

2025-09-02T20:09:16.864955434Z stderr: Invalid function: No module named 'numpy'

I can see that someone has asked a similar question here but I don’t think I have made a mistake with my folder names as this person has.

Please could someone enlighten me?