Load `env` from files

It would be awesome if env could be loaded from a file. Example:

name: Loading env vars from file
on:
  push:
    branches:
      - develop

env-file: dev.env
env:
  other-env-var: env-var-value

jobs:
  build:
    ...

[rgstephens]

Ended up doing it with the shell:

      - name: Import environment variables from a file
        id: import-env
        shell: bash
        run: |
          while read line; do
            echo "$line" >> $GITHUB_ENV
          done < ${{ env.ENV_FILE }}

[typebrook]

Ended up doing it with the shell:

      - name: Import environment variables from a file
        id: import-env
        shell: bash
        run: |
          while read line; do
            echo "$line" >> $GITHUB_ENV
          done < ${{ env.ENV_FILE }}

Why not just use cat?

run: cat ${{ env.ENV_FILE }} >> $GITHUB_ENV

or

run: < ${{ env.ENV_FILE }} >> $GITHUB_ENV