The translation "bisogna resistere" is helpful, if that somehow can link "phote manten" somehow to Petrarch, if "il faut mantenir", the French, doesn't do the trick.
The second link you gave doesn't get me to Petrarch. It gets me to Camillo Scroffa, a poet in the Petrarchan tradition of the mid 16th century. That is considerably later than the deck in question, the Brera-Brambilla. Also, I don't see him quoted with that phrase either.
Searching on Google for a connection to Petrarch, all I find is Italian Wikipedia on Atarassia,
https://it.wikipedia.org/wiki/Atarassia, which gives the phrase "bisogna resistere" to the Stoic Epictetus, presumably its Latin equivalent. That it occurs in relation to ataraxia--calmness-- is itself interesting, since the Greek original is atarachos, the opposite of tarachos, a word that could describe the tarocco player. But I am no nearer to Petrarch, except as someone else's description of the Petrarchan attitude toward ideal beauty, in a phrase from Epictetus.
I do not doubt that there is a connection, and I understand better the "what". But I want to know the "where", in Petrarch or his pre-1450 followers, to that Stoic expression, in any language.