`setup.py` improved in 07ad4afce29aaab8e053c30d46d6f28692c5d009, and released in v1.0.1. With a not-too-outdated version of pip, it should now refuse to install `caterpillar-hls` outright on Python <3.6.
Line 46 of `caterpillar.py` is the end of an f-string [1], available starting from Python 3.6. It appears you're using Python 3.5 or earlier. README does say Python 3.6 or later required. You can check your Python version with `python3 --version`, or, using the pip with which you installed `caterpillar-hls`: `pip --version`.
I should probably add a version check to `setup.py` to fail outright on Python 3.5 or earlier.
[1] https://docs.python.org/3/whatsnew/3.6.html#whatsnew36-pep498