Docker Build Error

[tolgayan]

I have encountered with the following error when I followed the installation guide in README file:

$ sudo docker build -t tagger .
Sending build context to Docker daemon  3.316MB
Step 1/6 : FROM python:2.7.11
 ---> a047e3d0ae2b
Step 2/6 : COPY . /turkish-pos-tagger
 ---> Using cache
 ---> 9ad831634ab3
Step 3/6 : WORKDIR /turkish-pos-tagger
 ---> Using cache
 ---> 2512070eff47
Step 4/6 : RUN pip install pyyaml
 ---> Using cache
 ---> 81bf848eed24
Step 5/6 : RUN pip install -U nltk
 ---> Running in 962d7405c371
Collecting nltk
  Downloading https://files.pythonhosted.org/packages/92/75/ce35194d8e3022203cca0d2f896dbb88689f9b3fce8e9f9cff942913519d/nltk-3.5.zip (1.4MB)
Collecting click (from nltk)
  Downloading https://files.pythonhosted.org/packages/d2/3d/fa76db83bf75c4f8d338c2fd15c8d33fdd7ad23a9b5e57eb6c5de26b430e/click-7.1.2-py2.py3-none-any.whl (82kB)
Collecting joblib (from nltk)
  Downloading https://files.pythonhosted.org/packages/ef/e9/80bdaef3848e8aa5e518f516bdfb79cc5d81c57ead939c541c20eecd7633/joblib-0.17.0.tar.gz (1.7MB)
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-OUiUtO/joblib/setup.py", line 6, in <module>
        import joblib
      File "/tmp/pip-build-OUiUtO/joblib/joblib/__init__.py", line 113, in <module>
        from .memory import Memory, MemorizedResult, register_store_backend
      File "/tmp/pip-build-OUiUtO/joblib/joblib/memory.py", line 274
        raise new_exc from exc
                         ^
    SyntaxError: invalid syntax
    
    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-OUiUtO/joblib/
You are using pip version 8.1.2, however version 20.2.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
The command '/bin/sh -c pip install -U nltk' returned a non-zero code: 1