Hi,
I have succesfully loaded your project. At the beggining it was givving me the error you have mentioned at the original post.
So I uploaded the .tflite file into netron.app and saw:

Screenshot 2021-12-04 at 17.01.242630×1114 167 KB

You see that the model is expecting one item in the float array.
So I changed your code to:
private void runInference()  {
        long t0 = System.currentTimeMillis();
        String path = this.fragment.getPath();
        if (path.length()==0) {
            displayMessage("No file has been selected yet");
        }

        try {
            TensorBuffer tb = TensorBuffer.createFixedSize(new int[]{1, 1}, DataType.FLOAT32);
            double features[] = {0.195312};
            ByteBuffer bb = ByteBuffer.allocate(features.length * 4);
            for (double f : features)
                bb.putFloat((float) f);
            tb.loadBuffer(bb);

            LinearRegression model = LinearRegression.newInstance(this);
            LinearRegression.Outputs outputs = model.process(tb);
            TensorBuffer outputFeature = outputs.getOutputFeature0AsTensorBuffer();
            float[] data = outputFeature.getFloatArray();
            int[] ret = new int[data.length];
            for (int i = 0 ; i < data.length; i++)
            {
                ret[i] = (int) data[i];
            }

            displayMessage("finished");
        } catch (Throwable t) {
            // TODO Handle the exception
            Log.d("ERROR", t.getMessage());
        }
    }

and it finishes correctly without errors.

Screenshot 2021-12-04 at 17.00.482142×792 101 KB

I do not know if there is a mistake when you have converted your model to .tflite file. Take a look at your colab and if you have issues ping me back.
Happy coding!