Use correct indentation for snapcraft.yaml

.editorconfig

@@ -11,6 +11,6 @@ trim_trailing_whitespace = true
 
 # The indent size used in the `package.json` file cannot be changed
 # https://github.com/npm/npm/pull/3180#issuecomment-16336516
-[{.travis.yml,npm-shrinkwrap.json,package.json}]
+[{.travis.yml,npm-shrinkwrap.json,package.json,snapcraft.yaml}]
 indent_style = space
 indent_size = 2