[ImgBot] Optimize images

*Total -- 965.47kb -> 753.07kb (22%)

/mails/pre_release_week_1/strategies.png -- 64.84kb -> 40.11kb (38.14%)
/mails/pre_release_week_1/rewards.png -- 116.21kb -> 85.00kb (26.86%)
/mails/pre_release_week_1/learn.png -- 192.95kb -> 141.48kb (26.67%)
/mails/pre_release_week_1/app-dashboard.png -- 43.09kb -> 32.13kb (25.43%)
/mails/pre_release_week_1/app-explorer.png -- 181.17kb -> 136.83kb (24.47%)
/mails/pre_release_week_1/news.png -- 367.21kb -> 317.52kb (13.53%)

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Author: ImgBotApp