Bump mkdocs-material website dependency to ^7.2.4

[per1234]

I have reviewed the changes and found nothing of concern.

This is the version now in use for the Arduino Lint website without problems: arduino/arduino-lint#256

"dev" deployment using mkdocs-material@7.2.4:

• https://github.com/arduino/arduino-lint/actions/runs/1123035833
• https://arduino.github.io/arduino-lint/dev/

Test release deployment in my fork using mkdocs-material@7.2.4:

• https://github.com/per1234/arduino-lint/actions/runs/1123028041
• https://per1234.github.io/arduino-lint/1.3/