title: Can't build docker image (it gives error in requirements.txt)
body: <p>i have been woek on a project and i had a problem which is really annoying.
  I have tried so many ways to get rid off it .
  I tried to install manually from requirements.txt after that it gives same error.I tried upgrade pip3 but my pip3 is latest version.
  I tried restart the subsystem etc. so it didn't work</p>
  <p>When i run command:</p>
  <pre><code>docker build -t main-app .
  </code></pre>
  <p>it gives me this error down bellow:</p>
  <p><a href="https://i.stack.imgur.com/SIDWm.png" rel="nofollow noreferrer">error image</a></p>
  <p>this is my requirements.txt:</p>
  <pre><code>aiodns==3.0.0
  aiohttp==3.7.4.post0
  aiohttp-socks==0.6.0
  async-timeout==3.0.1
  attrs==19.3.0
  Automat==0.8.0
  beautifulsoup4==4.9.3
  blinker==1.4
  cchardet==2.1.7
  certifi==2019.11.28
  cffi==1.14.5
  chardet==3.0.4
  Click==7.0
  cloud-init==21.2
  colorama==0.4.3
  command-not-found==0.3
  configobj==5.0.6
  constantly==15.1.0
  cryptography==2.8
  cssselect==1.1.0
  dbus-python==1.2.16
  distro==1.4.0
  distro-info===0.23ubuntu1
  elasticsearch==7.13.1
  entrypoints==0.3
  fake-useragent==0.1.11
  geographiclib==1.50
  geopy==2.1.0
  googletransx==2.4.2
  h2==3.2.0
  hpack==3.0.0
  httplib2==0.14.0
  hyperframe==5.2.0
  hyperlink==19.0.0
  idna==2.8
  importlib-metadata==1.5.0
  incremental==16.10.1
  itemadapter==0.2.0
  itemloaders==1.0.4
  Jinja2==2.10.1
  jmespath==0.10.0
  jsonpatch==1.22
  jsonpointer==2.0
  jsonschema==3.2.0
  keyring==18.0.1
  language-selector==0.1
  launchpadlib==1.10.13
  lazr.restfulclient==0.14.2
  lazr.uri==1.0.3
  lxml==4.6.3
  MarkupSafe==1.1.0
  more-itertools==4.2.0
  multidict==5.1.0
  netifaces==0.10.4
  numpy==1.20.3
  oauthlib==3.1.0
  p5py==1.0.0
  pandas==1.2.4
  parsel==1.6.0
  pep517==0.10.0
  pexpect==4.6.0
  priority==1.3.0
  Protego==0.1.16
  pyasn1==0.4.2
  pyasn1-modules==0.2.1
  pycairo==1.20.1
  pycares==4.0.0
  pycparser==2.20
  PyDispatcher==2.0.5
  PyGObject==3.36.0
  PyHamcrest==1.9.0
  PyJWT==1.7.1
  pymacaroons==0.13.0
  PyNaCl==1.3.0
  pyOpenSSL==19.0.0
  pyrsistent==0.15.5
  pyserial==3.4
  PySocks==1.7.1
  python-apt==2.0.0+ubuntu0.20.4.4
  python-dateutil==2.8.1
  python-debian===0.1.36ubuntu1
  python-socks==1.2.4
  pytz==2021.1
  PyYAML==5.3.1
  queuelib==1.6.1
  requests==2.22.0
  requests-unixsocket==0.2.0
  schedule==1.1.0
  Scrapy==2.5.0
  SecretStorage==2.3.1
  service-identity==18.1.0
  simplejson==3.16.0
  six==1.14.0
  sos==4.0
  soupsieve==2.2.1
  ssh-import-id==5.10
  systemd-python==234
  toml==0.10.2
  twint==2.1.20
  Twisted==18.9.0
  typing-extensions==3.10.0.0
  ubuntu-advantage-tools==20.3
  ufw==0.36
  unattended-upgrades==0.1
  zipp==1.0.0
  zope.interface==4.7.1
  </code></pre>
  <p>This is my Dockerfile:</p>
  <pre><code>FROM python:3.8-slim-buster
  
  WORKDIR /main
  
  COPY requirements.txt requirements.txt
  
  RUN  pip3 install --upgrade pip==21.1.2 setuptools
  
  RUN pip3 install Scrapy
  
  RUN pip3 install twint
  
  RUN pip3 install -r requirements.txt
  
  
  
  COPY . .
  
  CMD [ &quot;python3&quot;, &quot;./main.py&quot;]
  </code></pre>
  <p>This is my project structure down bellow:</p>
  <p><a href="https://i.stack.imgur.com/qWQUu.png" rel="nofollow noreferrer">Project Structure</a></p>