Sample Package.xml:
<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<members>LogACall</members><!--Global Action --> <members>Task.TestingAction</members><!--Object Quick Action -->
<name>QuickAction</name>
</types>
<version>36.0</version>
</Package>
Cheers!!!
<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<members>LogACall</members><!--Global Action --> <members>Task.TestingAction</members><!--Object Quick Action -->
<name>QuickAction</name>
</types>
<version>36.0</version>
</Package>
Cheers!!!