Error installing manim and running a test program

Describe the error

I installed ffmpeg from the APT package manager and PyOpenGL from pip3 in a virtual environment. Then, when I tried to install manim in the same virtual environment it gave the following error

However, in the end, it said that it successfully installed manim and its dependencies.

Then, I tried to run a simple program to see if it works:

But, it just keeps running with no errors (like it is frozen).

Code and Error

Code:

 class SquareImage(Scene):
 def construct(self):
square = Square()
self.add(square)

manimgl manim_test.py SquareImage -s

Error:

ERROR: Command errored out with exit status 1:
   command: /home/karan/manim/venv/bin/python /home/karan/manim/venv/lib/python3.8/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmp8troxa62
       cwd: /tmp/pip-install-vtkpor5m/manimpango_d759c30457a744afbb343d792b24d300
  Complete output (33 lines):
  Package pangocairo was not found in the pkg-config search path.
  Perhaps you should add the directory containing `pangocairo.pc'
  to the PKG_CONFIG_PATH environment variable
  No package 'pangocairo' found
  Traceback (most recent call last):
    File "setup.py", line 124, in check_min_version
      check_call(command, stdout=subprocess.DEVNULL)
    File "/usr/lib/python3.8/subprocess.py", line 364, in check_call
      raise CalledProcessError(retcode, cmd)
  subprocess.CalledProcessError: Command '['pkg-config', '--print-errors', '--atleast-version', '1.30.0', 'pangocairo']' returned non-zero exit status 1.
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/home/karan/manim/venv/lib/python3.8/site-packages/pip/_vendor/pep517/_in_process.py", line 280, in <module>
      main()
    File "/home/karan/manim/venv/lib/python3.8/site-packages/pip/_vendor/pep517/_in_process.py", line 263, in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
    File "/home/karan/manim/venv/lib/python3.8/site-packages/pip/_vendor/pep517/_in_process.py", line 114, in get_requires_for_build_wheel
      return hook(config_settings)
    File "/tmp/pip-build-env-vytjtzxg/overlay/lib/python3.8/site-packages/setuptools/build_meta.py", line 149, in get_requires_for_build_wheel
      return self._get_build_requires(
    File "/tmp/pip-build-env-vytjtzxg/overlay/lib/python3.8/site-packages/setuptools/build_meta.py", line 130, in _get_build_requires
      self.run_setup()
    File "/tmp/pip-build-env-vytjtzxg/overlay/lib/python3.8/site-packages/setuptools/build_meta.py", line 253, in run_setup
      super(_BuildMetaLegacyBackend,
    File "/tmp/pip-build-env-vytjtzxg/overlay/lib/python3.8/site-packages/setuptools/build_meta.py", line 145, in run_setup
      exec(compile(code, __file__, 'exec'), locals())
    File "setup.py", line 190, in <module>
      _pkg_config.check_min_version(MINIMUM_PANGO_VERSION)
    File "setup.py", line 127, in check_min_version
      raise RequiredDependencyException(f"{self.name} >= {version} is required")
  __main__.RequiredDependencyException: pangocairo >= 1.30.0 is required
  ----------------------------------------