software/erp5: don't use link for software-py3.cfg.json

this does not work when serving the raw blob on gitlab, so it is not
always usable for parameter editor.
8 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed Cloudooo.UnitTest-Master

00:12:13

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

00:42:56

failed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

15:02:57

passed SlapOS.Eggs.UnitTest-Master.Python2

00:25:14

passed SlapOS.Eggs.UnitTest-Master.Python3

00:25:23

failed SlapOS.SoftwareReleases.IntegrationTest-Master

12:33:18

passed SlapOS.Theia.ResilienceTest-Master-ERP5

10:16:20

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:42:25