I started my own research (sub) group in a STEM field some months ago at an EU university (bachelor/master/PhD system). Every student has to do a bachelor's thesis (6 weeks), research internships (total of 6 weeks), and a master's thesis (6 months). Since I believe that introducing students to actual research early is beneficial, I use these to let students work on part of my own research. This also allows me to care more about their work.
However, almost no female students show interest in doing their research projects in my group. I don't think it's because of me as person, since in the past almost 75% of students I supervised were women, most of them approaching me with the desire to work with me. However, I switched from an experimental research focus to a theoretical one and I require students to have some basic understanding of programming, since it's necessary for the research I'm doing now. I strongly suspect that this is the factor that leads to this problem.
Given the short time of many of those internships I don't see it as an option to teach these skills in that time in addition to the other necessary skills I have to convey. The university has coding courses and even special courses only for women, however, they don't seem to be very popular.
Any good ideas how I could motivate female students to pick up a basic knowledge in programming (either in the university provided courses or "on their own") and not being scared off by this requirement?