tolgaaaltas It's almost the same thing so it still needs to be attributed because they have license CC 3.0
I'll change the icon to something that doesn't require attribution in the next release when I get some free time. In the meantime people can enjoy the beauty of this icon while it lasts.
Edit: I haven't found anywhere where it says your are not supposed to use this icon for any reason, they only have rules for their logos like YouTube and Gmail. Plus I doubt the Google Flat icon page even belongs to Google as that page itself has copyrighten logos such as Facebook by Google, Instagram by Google and Twitter by Google.
So I think I won't be changing the logo for now.