The Google Drive API export_media() method does not accept the
supportsAllDrives parameter (unlike get(), list(), create(), etc.).
This caused export_doc_to_pdf to fail with:
"Got an unexpected keyword argument supportsAllDrives"
The fix removes the invalid parameter. File access for shared drives
is already validated by the preceding files().get() call which does
use supportsAllDrives=True.
Tested with Google Docs in shared drives - exports work correctly.
a4f0c66c55