Mounting Volume With `docker run`

I’m trying to setup CI/CD using gitea actions. My project has a Dockerfile containing the dev environment I use to build the application.

I’m trying to create an action which builds the dev container, then builds my project within it, and subsequently runs unit tests and whatnot. My workflow looks like the following:

jobs:
  Foo:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v3

    - name: Build image
      run: docker build -t project-env -f docker/Dockerfile .

    - name: Build application
      run: docker run --rm -v .:/workspace project-env './build.sh'

where workspace is the workdir specified in the Dockerfile. However, the CWD volume doesn’t appear to be mounted into the container, so the script which runs the build can’t be resolved. I’m just wondering whether I’m doing something silly here?