stack/erp5: backport a PyPDF fix

4 jobs for for_testrunner_1 in 0 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  External
failed ERP5.UnitTest-TestRunner1

03:50:08

passed SlapOS.Eggs.UnitTest-TestRunner1.Python2

02:16:45

passed SlapOS.Eggs.UnitTest-TestRunner1.Python3

02:21:39

passed SlapOS.SoftwareReleases.IntegrationTest-TestRunner1

08:39:27