Compound statements not supported in interpolations

[Nick Rolfe]

"#{ foo; bar }"

is accepted by MRI, but not by tree-sitter:

program [0, 0] - [1, 0])
  string [0, 0] - [0, 15])
    interpolation [0, 1] - [0, 14])
      method_call [0, 4] - [0, 12])
        method: identifier [0, 4] - [0, 7])
        ERROR [0, 7] - [0, 8])
        arguments: argument_list [0, 9] - [0, 12])
          identifier [0, 9] - [0, 12])

[Max Brunsfeld]

Fixed via #163