Github actions - issue using nvm install

I’m porting a project from travis to GH actions and very nearly complete, just having trouble getting nvm to behave as expected.

My action looks like this;

name: Frontend

on: [push]

jobs:
  frontend:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [6.x]

    steps:
    - uses: actions/checkout@v2
    - name: Use Node.js ${{ matrix.node-version }}
      uses: actions/setup-node@v1
      with:
        node-version: ${{ matrix.node-version }}
    - name: Setup nvm
      run: nvm install 8.10.0 && nvm use 8.10.0
    - name: Setup npm
      run: |
        npm config set spin false
        npm install -g npm
    - name: Install gulp
      run: npm install -g gulp@3.9.1
    - name: Install dependencies
      run: npm install
    - name: Run gulp
      run: gulp ci

This is failing with nvm: command not found so I added a couple of steps to debug;

    - name: check nvm location
      shell: bash -l -eo pipefail {0}
      run: echo $NVM_DIR

    - name: test nvm command
      shell: bash -l -eo pipefail {0}
      run: nvm ls

Now these both show that it is available with the ls outputting as follows;

>> Run nvm ls
               
->       system *
default -> system *
iojs -> N/A (default)
node -> stable (-> N/A) (default)
unstable -> N/A (default)

So if it can nvm ls what’s wrong with nvm install!?