Fix CSS selector for busy execution indicator

Author: krassowski

atest/05_Features/Completion.robot

@@ -12,7 +12,7 @@ Force Tags          feature:completion
 ${COMPLETER_BOX}            css:.jp-Completer.jp-HoverBox
 ${DOCUMENTATION_PANEL}      css:.jp-Completer-docpanel
 ${KERNEL_BUSY_INDCA_OLD}    css:.jp-NotebookPanel-toolbar div[title="Kernel Busy"]
-${KERNEL_BUSY_INDICATOR}    css:.jp-Notebook-ExecutionIndicator div[data-status="busy"]
+${KERNEL_BUSY_INDICATOR}    css:.jp-Notebook-ExecutionIndicator[data-status="busy"]
 
 
 *** Test Cases ***