Regardless of which language or software is used, there is more to this problem than meets the eye, and the OP will benefit from doing some reading on this old problem (Falkner Skan equation from fluid dynamics).
The Runge-Kutta method is primarily an algorithm for IVPs (Initial Value Problem). The present problem, however, is a BVP (boundary value problem).
One method for solving this BVP is to solve a sequence of IVPs with different values of f’’(0), aiming to satisfy the condition f’(infinity) = 1. This is the so called “shooting method”.
There are other algorithms for BVPs, as well.
[Added on 8 November 2021] I used the BVP solver of Shampine, Muir and Xu and found the solution f’’(0) = 1.23259, which agrees with the solution given in page 156, Table 3.4 of https://engineering.purdue.edu/~aerodyn/AAE416/Spring%202010/StagPt/NotesFromWhite.pdf .