Did you get a chance to

• check that the credentials you’re using to deploy have the necessary permissions to upload to the specified repository.
• check for the correctness of server credentials in settings.xml under .m2\

    <servers>
      <server>
        <id>sigit-releases</id>
        <username>your-username</username>
        <password>your-password</password>
      </server>
      <server>
        <id>sigit-snapshots</id>
        <username>your-username</username>
        <password>your-password</password>
      </server>
    </servers>