If you've been squatting 3x a week already for a while you should be able to recover from adding another day. Also, if you squat 3x a week the alternative is to do something like:
Day 1 5x5 (current weight but for 5 sets)
Day 2 3x3 (heavy triples)
Day 3 3x5 (with a slightly lighter weight than Day 1, focus on speed and technical perfection)
Don't increase Day 3's weight until you're just killing the speed on it. Just try to get faster week to week. Focus on hitting your reps on the other two days.
If you're using good form and hitting good depth 130 kg for 5 at 75 kg bodyweight isn't bad.
At this point squatting 5 days a week might not be necessary. On the other hand, if you hate days off there's no reason not to do it!
I suggest, however, doing 4 days a week for a month before going to 5. 4 days a week for 4 weeks, then deload the weights by about 40% on week 5 but still keep the frequency, then hit 5 days a week on week six.