message: chore: use env var for running tests in series
diff: @@ -16,7 +16,7 @@ const tests = testTypes.map(cmd => {
  let tests = _(['plain', 'mocha', 'typescript', 'everything'])
  .map(t => [t, `test/commands/${cmd}/${t}.test.js`])
  .map(([t, s]) => [t, process.env.CIRCLECI ? `MOCHA_FILE=reports/mocha-${t}.xml ${mocha} --reporter mocha-junit-reporter ${s}` : `${mocha} ${s}`])
  - tests = process.platform === 'win32' ?
  + tests = process.env.TEST_SERIES === '1' ?
  series(...tests.map(t => t[1]).value()) :
  concurrent(tests.fromPairs().value())
  if (process.env.CIRCLECI) {
  