Encourage students to be independent
I think there's a few different skills students need for independence, and they require quite different teaching approaches. Independence is the end result but you can't teach it directly. 


Confidence. They need to think it's possible to try out a new toolset and make something. Guiding them prescriptively through a variety of different new tools is a good way to do this, as with @BrDaHa's answer. i.e. Don't teach independence as such but show through example that different and new approaches are possible and not too difficult. Once they've achieved several different projects, even tiny ones, with different technologies they'll be more confident to explore different options rather than use the same thing every time. 
Abstract understanding. The hard bit of programming is thinking about problems and solutions in the right way. Once you know conceptually what you want to do it's much less scary to go find a tool to implement that well, and that conceptual understanding will help guide you through using a new tool. Teaching CS generally addresses this, plus a specific focus on systems design. 
Ability to learn something they don't already know. Reading documentation, using stack overflow, reading blog posts and books. Students need to learn each of these, they're different skills, and they're often not taught well or at all in CS courses. When you can do these things then approaching a new tech is fun rather than daunting. 
Appreciate there's different tools for different jobs. You need to demonstrate, or better have them experience, that some technologies are great for some things and not others. So they know there's worthwhile in exploring different tech. On the one hand, when you have a hammer everything looks like a nail. Conversely though, it's often a lot faster to use a tool you know than learn a whole new one for a small job, even if that tool is 'better'. Negotiating that trade off is an important part of general software development. Part of the fun of being a developer.