KNX fix javascript scrumbled by quote char

[barbudor]

Description:

Related issue (if applicable): fixes #16707

Javascript alert('" D_KNX_WARNING '"); was broken by Italian translation introducing a ' in the text
Replaced the single-quote by double-quote in the Javascript code

@bovirus Thanks a lot for this one. It took me 2 hours to figure it out 🤣
Please do not PR translation for features that you have not tested !

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.4.9
• The code change is tested and works with Tasmota core ESP32 V.2.0.5
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[barbudor]

ping @platini76 for merging

[ascillato2]

Good one!!! Thanks for fixing.