Is there anyway to calculate the next seed knowing the previous seed?
The reason that pseudorandom number generators are so named is that they're deterministic; they generate a sequence of numbers that appear to be random, but which aren't really. If you start a PRNG with the same seed, you'll get the same sequence every time.

I already have a programm that gets the seed of the previous generated number using seed = random.getstate()

You're not really getting a seed here, but rather the internal state of the PRNG. You could save that state and set it again later. That could be useful for testing, or just to continue with the same sequence.

Now, my question is if there is anyway to calculate the next seed that will be used, so I can predict the number.

Again, not really a seed, which is the initial value that you supply to start a PRNG sequence. What you're getting is the internal state of the PRNG. But yes, if you have that state, then it's trivial to predict the next number: just call random.setstate(...) with the state that you got, generate the next number, and then call random.setstate(...) again to put the PRNG back in the same state so that it'll again generate that same number.
I'm trying to develop a program in Python to predict the outcome of a Pseudo Random Number Generator.
I already have a program that gets the seed of the previously generated number using seed = random.getstate(). My question is whether there is any way to calculate the next seed that will be used, so I can predict the next number.