putting back xvfb-run in casa call

apps/cli/executables/pexable/casa_envoy/casa_envoy/palaver.py

@@ -40,9 +40,10 @@ class CalibrationLauncher(CasaLauncherIF):
     def run(self):
         logger.info("RUNNING CASA!")
         os.chdir("./working")
-        result = subprocess.Popen("${CASA_HOME}/bin/casa --pipeline --nogui --nologger -c "
+        result = subprocess.Popen("PYTHONPATH='' xvfb-run -e ${PWD}/xvfb-run.err.txt -d -s \"-screen 0 800x600x16\" "
+                                  "${CASA_HOME}/bin/casa --pipeline --nogui --nologger -c "
                                   "${CASA_HOME}/pipeline/pipeline/runvlapipeline.py ${PPR_FILENAME} || true",
-                         shell=True, executable="/bin/bash", stdout=sys.stdout, stderr=sys.stderr)
+                                  shell=True, executable="/bin/bash", stdout=sys.stdout, stderr=sys.stderr)
         return result.communicate()
 
     def setup_environment(self, parameters: dict):