text: Title: Can't install normally pyqt5
  Body: `pip install pix2tex[gui]`
  gives me
  ```
  ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
   spyder 5.1.5 requires pyqt5<5.13, but you have pyqt5 5.15.6 which is incompatible.
   spyder 5.1.5 requires pyqtwebengine<5.13, but you have pyqtwebengine 5.15.5 which is incompatible.
   Successfully installed PyQt5-5.15.6 PyQt5-sip-12.10.1
  ```
  if i ignore it and enter
  `latexocr --gnome`
  it gives me
  ```
  Traceback (most recent call last):
  File "/home/islambek243/anaconda3/bin/latexocr", line 5, in <module>
  from pix2tex.gui import main
  File "/home/islambek243/anaconda3/lib/python3.9/site-packages/pix2tex/gui.py", line 7, in <module>
  from PyQt5.QtWebEngineWidgets import QWebEngineView
  ImportError: /usr/lib/x86_64-linux-gnu/libgssapi_krb5.so.2: undefined symbol: krb5_ser_context_init, version krb5_3_MIT
  ```
  If i don't ignore previous error and enter
  `pip install pyqt5==5.12.3`
  it gives me
  ```
  ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
  spyder 5.1.5 requires pyqtwebengine<5.13, but you have pyqtwebengine 5.15.5 which is incompatible.
  pyqtwebengine 5.15.5 requires PyQt5>=5.15.4, but you have pyqt5 5.12.3 which is incompatible.
  Successfully installed pyqt5-5.12.3
  ```
  it's endless circle...