Add requirements.txt with linters/formatters that can be installed from PyPI

[abelsiqueira]

We could put the things you can get from pypi into a requirements.txt

_Originally posted by @jspaaks in https://github.com/nlesc-recruit/CUDA-wrappers/pull/77#discussion_r816741332_

[fdiblen]

Also update the developer documentation.

[jspaaks]

Alternatively, maybe we can just add a note to the README.dev.md, something along th elines of

# install cppcheck, clang-tidy, clang-format from your package manager
sudo apt install cppcheck clang-format clang-tidy

# install python3 and pip
sudo apt install python3 python3-pip

# install flawfinder, cmake-format, cmake-lint from PyPI using pip
python3 -m pip install flawfinder cmake-format cmake-lint 

[fdiblen]

Alternatively, maybe we can just add a note to the README.dev.md, something along th elines of

# install cppcheck, clang-tidy, clang-format from your package manager
sudo apt install cppcheck clang-format clang-tidy

# install python3 and pip
sudo apt install python3 python3-pip

# install flawfinder, cmake-format, cmake-lint from PyPI using pip
python3 -m pip install flawfinder cmake-format cmake-lint 

I think this will be cleaner so yes!

[fdiblen]

fixed by #105