xcode.sh 修正

`xcode/xcode.sh` 失敗してる
```
> xcodebuild
Command line invocation:
    /Applications/Xcode-12.4.0.app/Contents/Developer/usr/bin/xcodebuild

xcodebuild: error: The directory /$HOME/ghq/github.com/ry-itto/dotfiles does not contain an Xcode project.
```