Fix pdf export

lib/frontend/jlb_io.py

@@ -640,7 +640,7 @@ def export_nb_to_pdf(path_to_nb, timeout=100., verbose=True,
             command+= path_to_nb
             command+= ' --output-dir %s'%output_dir
             command+= ' --to pdf '
-            command+= ' --TagRemovePreprocessor.remove_cell_tags \'notPrint\' ' # Remove the widgets from the PDF
+            command+= ' --RegexRemovePreprocessor.patterns=\"[\'#notPrint\']\" ' # Remove the widgets from the PDF
             command+= ' --no-input ' # Remove the code cells
             #command+= '--template latex_template.tplx' # Custom template (not working with nbconvert >= 6.0)
             command+= ' --PDFExporter.latex_command="[\'xelatex\', \'{filename}\']"> nbconvert.log 2>&1' # Write the log in a file