software/slapos-sr-testing: install theia test egg

Otherwise it's installed by python setup.py outside of buildout

software/slapos-sr-testing/software.cfg

@@ -184,6 +184,7 @@ eggs =
   ${slapos.test.jupyter-setup:egg}
   ${slapos.test.nextcloud-setup:egg}
   ${slapos.test.turnserver-setup:egg}
+  ${slapos.test.theia-setup:setup}
   ${slapos.test.cloudooo-setup:egg}
   ${slapos.test.dream-setup:egg}
   ${backports.lzma:egg}