```ruby
class Imagealpha < Cask
  url 'http://pngmini.com/ImageAlpha1.2.5.1.tar.bz2'
  homepage 'http://pngmini.com/'
  version '1.2.5.1'
  sha1 '46672dac88acf5c91d35b74757b1d636048da7a6'
end
```

Update cask to latest version.
user
```ruby
class Imagealpha < Cask
  url 'http://pngmini.com/ImageAlpha1.3.0.6.tar.bz2'
  homepage 'http://pngmini.com/'
  version '1.3.0.6'
  sha1 '1cb44cd72245e112f146ace5d8685d727f777bdc'
end
```
assistant