Update de_web_plugin.cpp
Update de_web_plugin.cpp

Change fix for #4249: now calling `rx()` before calling `writeAttribute()`.

dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin