According to the datasheet from your selected MCU (STM32F103C8T6) the device doesn't support the I2S interface. It supports only two normal SPI interfaces. You need a high-density device in the SM32F103xx series. STM32F103VG as an example, but it use a TQFP100 package.

Source: STM32F103xx Datasheet

You can also see this in the STM32F103 product selector, that the STM32F103C8 doesn't supports I2S.