Installation failure on Mac

[aleReimondo]

pip install -r requirements.txt
on macOS Monterrey fail to install mpmath
How to avoid the issue? When/why this specific version of library is required? (and not the latest version)
It sound like a classic weakness of using python (no compromise with time of others spent in making code run as expected)

---

Collecting mpmath>=0.19 (from sympy->torch>=1.7.0->fastai==2.1.5->-r requirements.txt (line 19))
Using cached mpmath-1.3.0-py3-none-any.whl (536 kB)
Building wheels for collected packages: llvmlite, scikit-learn
Building wheel for llvmlite (setup.py) ... error
error: subprocess-exited-with-error

× python setup.py bdist_wheel did not run successfully.
│ exit code: 1
╰─> [26 lines of output]
running bdist_wheel
/Library/Developer/CommandLineTools/usr/bin/python3 /private/var/folders/k9/0_x3kkms3rxgthtqsp3vsjph0000gn/T/pip-install-05jt04o7/llvmlite_10c0b3e5d26c40d4ad1916ecb7155298/ffi/build.py
LLVM version... Traceback (most recent call last):
File "/private/var/folders/k9/0_x3kkms3rxgthtqsp3vsjph0000gn/T/pip-install-05jt04o7/llvmlite_10c0b3e5d26c40d4ad1916ecb7155298/ffi/build.py", line 105, in main_posix
out = subprocess.check_output([llvm_config, '--version'])
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/subprocess.py", line 424, in check_output
return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/subprocess.py", line 505, in run
with Popen(*popenargs, **kwargs) as process:
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/subprocess.py", line 951, in init
self._execute_child(args, executable, preexec_fn, close_fds,
File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/subprocess.py", line 1821, in _execute_child
raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'llvm-config'