Remove Macast

[StarsbySea]

As the official Extras bucket already contains the Macast App and the App's profile in this bucket is largely indistinguishable from the official one, it is recommended to remove the App's profile.

extras https://github.com/ScoopInstaller/Extras/blob/master/bucket/macast.json
dorado https://github.com/chawyehsu/dorado/blob/master/bucket/macast.json

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由于官方的Extras仓库已经收录了Macast App，并且该App在本仓库的配置文件和官方的基本无差别，所以推荐移除该App的配置文件。

extras https://github.com/ScoopInstaller/Extras/blob/master/bucket/macast.json
dorado https://github.com/chawyehsu/dorado/blob/master/bucket/macast.json