composer installで以下のエラーが出る場合。 Problem 1 - Installation request for maknz/slack 1.7.0 -> satisfiable by maknz/slack[1.7.0]. - maknz/slack 1.7.0 requires ext-mbstring * -> the requested PHP extension mbstring is missing from you…

composer installなどで以下のエラーが出る場合の対応。 [Composer\Exception\NoSslException] The openssl extension is required for SSL/TLS protection but is not available. If you can not enable the openssl extension, you can disable this error…