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
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
_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
----------------------------------------

```

### Environment
**OS System**: Linux Mint
**manim version**: master
**python version**: 3.8.5