Unable to mount docker to $(pwd) [exec]

Describe the bug
When mounting docker to $(pwd) with exec, the action failed and I got:

/usr/bin/docker: Error response from daemon: create $(pwd): "$(pwd)" includes invalid characters for a local volume name, only "[a-zA-Z0-9][a-zA-Z0-9_.-]" are allowed. If you intended to pass a host directory, use absolute path.

Command called:

const cmd= "docker run -v $(pwd):/tmp tiagogouvea/dpl:v1.10.15 --provider='heroku' ";
await exec.exec(cmd);

ℹ️ Running the same command using child_process.execSync works. Example:

const cmd= "docker run -v $(pwd):/tmp tiagogouvea/dpl:v1.10.15 --provider='heroku' ";
execSync(cmd);

To Reproduce
Steps to reproduce the behavior:

1. Create a action with JavaScript
2. Call await exec.exec("docker run -v $(pwd):/tmp tiagogouvea/dpl:v1.10.15");

Expected behavior

• Want to mount the current path to as docker volume.
• Wanted to @actions/exec work like child_process/execSync.

Desktop (please complete the following information):

• OS: runs-on: ubuntu-latest

Start at the @actions/exec entry point used by exec.exec and compare its command handling with Node's child_process.execSync, using the Docker command and error in the report as the reproduction. Done means the documented current-path Docker volume command behaves as expected, with coverage or clarified behavior for shell command substitution.