[ImgBot] Optimize images

*Total -- 507.50kb -> 373.56kb (26.39%)

/software_screenshots/device_0.png -- 9.10kb -> 4.01kb (55.9%)
/software_screenshots/alexa_config.png -- 59.67kb -> 26.63kb (55.38%)
/software_screenshots/board_manager.png -- 25.52kb -> 14.09kb (44.76%)
/software_screenshots/arduinoJson.png -- 31.64kb -> 17.55kb (44.53%)
/software_screenshots/ota.png -- 30.75kb -> 17.61kb (42.72%)
/software_screenshots/mqtt.png -- 27.84kb -> 15.97kb (42.64%)
/software_screenshots/config.png -- 96.56kb -> 60.75kb (37.09%)
/web_ui.jpg -- 226.43kb -> 216.95kb (4.18%)

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