software/theia: Adapt upgrade tests

Older Theia versions no longer compile inside test nodes since we
prevent using the system python.

software/theia/test/upgrade_tests.py

@@ -11,7 +11,7 @@ import test
 import test_resiliency
 
 
-stable_software_url = "https://lab.nexedi.com/nexedi/slapos/raw/1.0.324/software/theia/software.cfg"
+stable_software_url = "https://lab.nexedi.com/nexedi/slapos/raw/1.0.349/software/theia/software.cfg"
 dev_software_url = os.path.abspath(
   os.path.join(os.path.dirname(__file__), '..', 'software.cfg'))