UbuntuのLaunchpad GPG署名検証エラーを修正
https://www.youtube.com/watch?v=u_LPScqsf9s&pp=ygU_IFVidW50deOBrkxhdW5jaHBhZCBHUEfnvbLlkI3mpJzoqLzjgqjjg6njg7zjgpLkv67mraMmaGw9e2xhbmd9
W GPG error The following signatures couldn't be verified because the public key is not available
https://how2.work/Ubuntu%E3%81%AELaunchpadGPG%E7%BD%B2%E5%90%8D%E6%A4%9C%E8%A8%BC%E3%82%A8%E3%83%A9%E3%83%BC%E3%82%92%E4%BF%AE%E6%AD%A3/
