Let's encrypt acme plugin 2.4

[fabiodanzetta]

Hi everebody,

we are running Opnsense 21.1.4 and we would like to install the acme plugin but we receive messagge saying "Installation out of date. The update to opnsense-21.1.5 is required."
Why we can't keep opnsense 21.1.4 and install this plugin and is necessary to update?
Why update is mandatory?

Thanks soo mutch.