add odoo 13 case for --odoo-sources

NEWS.rst

@@ -16,6 +16,8 @@
 
 🔨 Change list_modules command to output in the console when used.
 
+Handle option --odoo-sources in odoo 13.
+
 7.0.5
 -----
 

odoo_scripts/docker_dev_start.py

@@ -810,6 +810,8 @@
                 pythons = ("python2.7",)
             elif odoo_type == "odoo11":
                 pythons = ("python3.5", "python3.6")
+            elif odoo_type == "odoo13":
+                pythons = ("python3.8",)
             else:
                 pythons = ("python3.6",)
             for python in pythons: