I second what patio11 said about the low prevalence of modern frameworks. Even at the most advanced startups I've seen up close, more of the software is built using custom frameworks than using "cutting-edge" modern frameworks. Adopting each new modern framework has a cost, and if a startup's problems are largely orthogonal to the problems the framework solves, adopting the framework is unjustified. I can remember only one job interview where extensive Rails experience was a hard requirement, but it was probably because the company's founding team wanted help learning Rails. You should be able to find many jobs where experience with modern frameworks is not a hard requirement.
If I were in your situation, I'd do two things. First, I'd write a list of 10 ideas to make my career really fun. This list would probably describe companies to interview at and projects to pursue. Second, I'd write a list of 10 ideas to make my current job really fun. This might require some extreme creativity, but it might be better to make a possibly futile attempt to enjoy the current job while working on finding the next one than continue to waste away in misery.
Here are a few crazy ideas that come to mind. Your ideas will be better:
1. Make a bingo board where each square is a common annoyance you encounter in the code. Share combinations of the bingo board with your co-workers. Give a candy bar to whomever gets bingo first.
2. When faced with an annoying task, set a countdown timer and do everything you can to finish the task before the time runs out. Don't let the bomb explode.
3. Stand up and do a fist pump every time you make an especially clever commit.
4. Listen to music that is fun.
5. Periodically listen to comedy that makes you laugh.
6. Think of the people you admire or respect in your workplace. Try to meet with them and learn from them. Give back to them too - perhaps by giving them ideas that you think could possibly help them in their projects, or introduce them to people you know who could help them.
7. Bring in snacks or some particularly tasty treats to share with your co-workers. It might help build some emotional connection and friendship.
8. Bring a bag of M&Ms and eat one every time you save a file.
9. Try working for an hour using only one hand.
10. If you're in an office setting where talking out loud won't bother other people, try narrating everything you do during the work day like how YouTube stars narrate playing video games. An immensely talented engineer I knew at an internship would sing rap lyrics all morning and swear vigorously at his machine when things went badly wrong. It was ridiculously entertaining.
Best of luck making your career more enjoyable!