.circleci.settings.xml

<settings>
  <servers>
    <server>
      <id>ossrh</id>
      <username>${env.OSSRH_USERNAME}</username>
      <password>${env.OSSRH_PASSWORD}</password>
    </server>
    <server>
      <id>gpg.passphrase</id>
      <passphrase>${env.GPG_PASSPHRASE}</passphrase>
    </server>
  </servers>
</settings>