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.

software/erp5/software-py3.cfg.json

-software.cfg.json
\ No newline at end of file

software/erp5/software-py3.cfg.json

+{
+  "name": "ERP5",
+  "description": "ERP5, Open-Source ERP (using python3)",
+  "serialisation": "json-in-xml",
+  "software-type": {
+    "default": {
+      "title": "Default",
+      "software-type": "default",
+      "request": "instance-erp5-input-schema.json",
+      "response": "instance-erp5-output-schema.json",
+      "index": 0
+    }
+  }
+}