Fixed database environment variables leaking across matrix runs

refs TryGhost/Toolbox#244

- due to the way we currently set the env vars, they get applied across
  all matrix variations
- this means we're leaking the variables for SQLite to the MySQL test
  runs and this shows a warning because of how strict `mysql2` is
- this commit switches to optionally setting the env variables
- this is a partial workaround for https:/TryGhost/Ghost/blob/fbcdacbd8311c5842a7653813ea33fddc34acd77/core/shared/config/utils.js#L55-L76 not seeming to work

.github/workflows/test.yml

@@ -50,11 +50,6 @@ jobs:
  DB_CLIENT: mysql
  env:
  database__client: ${{ matrix.env.DB_CLIENT }}
- database__connection__filename: /dev/shm/ghost-test.db
- database__connection__host: 127.0.0.1
- database__connection__user: root
- database__connection__password: root
- database__connection__database: ghost_testing
  name: Migrations (${{ matrix.env.DB }})
  steps:
  - uses: actions/checkout@v2
@@ -87,6 +82,18 @@ jobs:
  mysql database: 'ghost_testing'
  mysql root password: 'root'
 
+ - name: Set env vars (SQLite)
+ if: contains(matrix.env.DB, 'sqlite')
+ run: echo "database__connection__filename=/dev/shm/ghost-test.db" >> $GITHUB_ENV
+
+ - name: Set env vars (MySQL)
+ if: contains(matrix.env.DB, 'mysql')
+ run: |
+ echo "database__connection__host=127.0.0.1" >> $GITHUB_ENV
+ echo "database__connection__user=root" >> $GITHUB_ENV
+ echo "database__connection__password=root" >> $GITHUB_ENV
+ echo "database__connection__database=ghost_testing" >> $GITHUB_ENV
+
  - run: yarn
  - run: |
  node index.js &
@@ -148,7 +155,6 @@ jobs:
  env:
  DB: ${{ matrix.env.DB }}
  NODE_ENV: ${{ matrix.env.NODE_ENV }}
- database__connection__password: root
  name: Database Tests (Node ${{ matrix.node }}, ${{ matrix.env.DB }})
  steps:
  - uses: actions/checkout@v2
@@ -182,10 +188,16 @@ jobs:
 
  - run: date +%s > ${{ runner.temp }}/startTime # Get start time for test suite
 
+ - name: Set env vars (SQLite)
+ if: contains(matrix.env.DB, 'sqlite')
+ run: echo "database__connection__filename=/dev/shm/ghost-test.db" >> $GITHUB_ENV
+
+ - name: Set env vars (MySQL)
+ if: contains(matrix.env.DB, 'mysql')
+ run: echo "database__connection__password=root" >> $GITHUB_ENV
+
  - name: Run tests
  run: yarn test:ci
- env:
- database__connection__filename: /dev/shm/ghost-test.db
 
  # Get runtime in seconds for test suite
  - run: |