Fix compile issue with limits

[semenko]

Fixes this small compile time error on Ubuntu 22.04 / Python 3.9:

$ python setup.py
< snip >

Compiling segmentor...
FAIL
Failed compilation.
Command: g++ -std=c++11 src/segment_betas/main.cpp src/segment_betas/segmentor.cpp -o src/segment_betas/segmentor
return code: 1
stderr:

stdout:
src/segment_betas/segmentor.cpp: In member function ‘void segmentor::cost_memoization(std::vector<float*>&)’:
src/segment_betas/segmentor.cpp:76:46: error: ‘numeric_limits’ is not a member of ‘std’
   76 |                 mem[i * max_cpg + j] = -std::numeric_limits<float>::infinity();
      |                                              ^~~~~~~~~~~~~~
src/segment_betas/segmentor.cpp:76:61: error: expected primary-expression before ‘float’
   76 |                 mem[i * max_cpg + j] = -std::numeric_limits<float>::infinity();
      |                                                             ^~~~~
src/segment_betas/segmentor.cpp: In member function ‘void segmentor::dp(std::vector<float*>&)’:
src/segment_betas/segmentor.cpp:139:35: error: ‘numeric_limits’ is not a member of ‘std’
  139 |         double best_score = -std::numeric_limits<float>::infinity();
      |                                   ^~~~~~~~~~~~~~
src/segment_betas/segmentor.cpp:139:50: error: expected primary-expression before ‘float’
  139 |         double best_score = -std::numeric_limits<float>::infinity();
      |                                                  ^~~~~

Failed compiling segmentor

[nloyfer]

Thank you