Install the 'wheel' package in sonic-slave-buster container to eliminate error messages like the following:
```
Running setup.py bdist_wheel for watchdog: started
Running setup.py bdist_wheel for watchdog: finished with status 'error'
Complete output from command /usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-install-Qd3K08/watchdog/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" bdist_wheel -d /tmp/pip-wheel-0AHpMe --python-tag cp27:
usage: -c [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...]
or: -c --help [cmd1 cmd2 ...]
or: -c --help-commands
or: -c cmd --help
error: invalid command 'bdist_wheel'
----------------------------------------
Failed building wheel for watchdog
```
These error messages appear to have no impact on the image build, because the Python package seems to still get installed successfully afterward, just the building of a wheel package fails. Therefore, this is more of a cosmetic fix than an actual bug.
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