Fix Numpy version

[JoseMLopezSanz]

The numpy version is not specified on the requirements file and the code doesn't run with 1.14 or 1.18, fixing it to 1.16 should solve the problem

[flackbash]

Currently, there are conflicting requirements for numpy. While installing the requirements, I get the error message:

The conflict is caused by:
    The user requested numpy==1.14.0
    scipy 1.0.0 depends on numpy>=1.8.2
    tensorflow-tensorboard 0.4.0 depends on numpy>=1.12.0
    tensorflow 2.5.0 depends on numpy~=1.19.2

And after setting numpy to v1.19.2

The conflict is caused by:
    The user requested requests==2.18.4
    tensorboard 2.8.0 depends on requests<3 and >=2.21.0
    The user requested requests==2.18.4
    tensorboard 2.7.0 depends on requests<3 and >=2.21.0
    The user requested requests==2.18.4
    tensorboard 2.6.0 depends on requests<3 and >=2.21.0
    The user requested requests==2.18.4
    tensorboard 2.5.0 depends on requests<3 and >=2.21.0

After setting requests to v2.21.0, there is a problem with scipy:

ERROR: Failed building wheel for scipy

I was able to install everything by changing the requirements to the following:

enum34==1.1.6
tensorflow-tensorboard==0.4.0
termcolor==1.1.0
tensorflow==2.5.0
gensim==3.1.0
nltk==3.4.5
numpy==1.19.2
requests==2.21.0

However, I ran into another problem that I reported in #38 so I'm not sure if everything will run through without errors after that.