Anyway, i would try to uninstall it and reinstall the package-manager version of pip, and then try it again without updating pip:
Using python3 -m pip install -r requirements.txt should work afterwards.
It fails here:Code:
sudo python3 -m pip uninstall pip && sudo apt-get install python3-pip --reinstall
Using python3 -m pip install -r requirements.txt should work afterwards.
Code:
Collecting websockets (from pyppeteer>=0.0.14->requests-html==0.10.0->-r requirements.txt (line 1))
Downloading https://files.pythonhosted.org/packages/79/78/17e97a159dc55308b1468a638c7267f19765281f6205ec9c15253c154022/websockets-8.0.2.tar.gz (57kB)
100% |################################| 61kB 12.8MB/s
Complete output from command python setup.py egg_info:
Traceback (most recent call last):
File "", line 1, in
File "/tmp/pip-build-9fhjti3j/websockets/setup.py", line 27, in
raise Exception("websockets requires Python >= 3.6.")
Exception: websockets requires Python >= 3.6.
----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-9fhjti3j/websockets/
You are using pip version 8.1.1, however version 19.2.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
Downloading https://files.pythonhosted.org/packages/79/78/17e97a159dc55308b1468a638c7267f19765281f6205ec9c15253c154022/websockets-8.0.2.tar.gz (57kB)
100% |################################| 61kB 12.8MB/s
Complete output from command python setup.py egg_info:
Traceback (most recent call last):
File "", line 1, in
File "/tmp/pip-build-9fhjti3j/websockets/setup.py", line 27, in
raise Exception("websockets requires Python >= 3.6.")
Exception: websockets requires Python >= 3.6.
----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-9fhjti3j/websockets/
You are using pip version 8.1.1, however version 19.2.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
Quote
By the way, which version of python3 and pip are you using?
Code:
python3 --version && pip3 --version
Code:
Python 3.5.2
pip 8.1.1 from /usr/lib/python3/dist-packages (python 3.5)
pip 8.1.1 from /usr/lib/python3/dist-packages (python 3.5)
Do you have Python 3.6? I completely forgot it was only available for that specific version of Python
My Python version older 
I give up for now, I've been busy fixing other stuff, but this VPS turns out to be too unstable for any serious use so I'll continue this when I have a better VPS.