(ioDcmtk): fix the series DB reader and the CI last modification time of file

What does this MR do?

Don't set m_readFailded to true in ioDcmtk::SSeriesDBReader when the folder is properly read.

Fix the last modification time of file in hte CI.

How to test it?

Try to read a DICOM folder with VRRender and the Dcmtk reader.

Associated Issues/Merge Requests

• Issues
  • Fixes #490 (closed)