Unicode double quotes on config.yaml file causes UnicodeDecodeError

I was in the process of upgrading from revision 812 to 826, when all the units went into error state due to the hook having failed.

Upon a closer look at one of the unit's logs:

2021-09-29 15:14:33 ERROR juju-log Hook error:
Traceback (most recent call last):
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/charms/reactive/__init__.py", line 73, in main
    hookenv._run_atstart()
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/charmhelpers/core/hookenv.py", line 1352, in _run_atstart
    callback(*args, **kwargs)
  File "lib/charms/layer/basic.py", line 480, in init_config_states
    config_defs = yaml.safe_load(fp).get('options', {})
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/yaml/__init__.py", line 162, in safe_load
    return load(stream, SafeLoader)
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/yaml/__init__.py", line 112, in load
    loader = Loader(stream)
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/yaml/loader.py", line 34, in __init__
    Reader.__init__(self, stream)
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/yaml/reader.py", line 85, in __init__
    self.determine_encoding()
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/yaml/reader.py", line 124, in determine_encoding
    self.update_raw()
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/site-packages/yaml/reader.py", line 178, in update_raw
    data = self.stream.read(size)
  File "/var/lib/juju/agents/unit-calico-1/.venv/lib/python3.6/encodings/ascii.py", line 26, in decode
    return codecs.ascii_decode(input, self.errors)[0]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 292: ordinal not in range(128)

And indeed, the config.yaml file has 4 double quotes typed with the unicode char 0x201d.

The obvious workaround of replacing those quotes per "regular" ones fixed the issue.