Fixed #23852 Magento 2.3 Customer Configuration in the Online Customers Options field validation

Author: kirtinariya1

app/code/Magento/Customer/etc/adminhtml/system.xml

@@ -289,10 +289,12 @@
                 <label>Online Customers Options</label>
                 <field id="online_minutes_interval" translate="label comment" type="text" sortOrder="1" showInDefault="1" showInWebsite="0" showInStore="0">
                     <label>Online Minutes Interval</label>
+                    <validate>validate-number</validate>
                     <comment>Leave empty for default (15 minutes).</comment>
                 </field>
                 <field id="section_data_lifetime" translate="label comment" type="text" sortOrder="1" showInDefault="1" showInWebsite="0" showInStore="0">
                     <label>Customer Data Lifetime</label>
+                    <validate>validate-number</validate>
                     <comment>Please specify value in minutes.</comment>
                 </field>
             </group>