if msgpack installed : ValueError: Invalid encoding `raw` given

[llicour]

if msgpack package (that is a newer version of msgpack-python) is already installed in venv, rma have the following backtrace

Traceback (most recent call last):
  File "/Users/xxx/.pyenv/versions/venv-py37/bin/rma", line 11, in <module>
    load_entry_point('rma', 'console_scripts', 'rma')()
  File "/Users/xxx/Documents/Workspace/redis-memory-analyzer/rma/cli/rma_cli.py", line 109, in main
    app.run()
  File "/Users/xxx/Documents/Workspace/redis-memory-analyzer/rma/application.py", line 127, in run
    for v in scanner.scan(limit=self.limit):
  File "/Users/xxx/Documents/Workspace/redis-memory-analyzer/rma/scanner.py", line 100, in scan
    'encoding': redis_encoding_str_to_id(key_encoding),
  File "/Users/xxx/Documents/Workspace/redis-memory-analyzer/rma/redis_types.py", line 58, in redis_encoding_str_to_id
    raise ValueError("Invalid encoding `%s` given" % key_encoding)
ValueError: Invalid encoding `raw` given

This is because of msgpack seems to return str instead of bytes
Adding bytes conversion could resolve that

def redis_encoding_str_to_id(key_encoding):
    key_encoding = key_encoding.encode("utf8")
    if key_encoding in REDIS_ENCODING_STR_TO_ID_LIB:
        return REDIS_ENCODING_STR_TO_ID_LIB[key_encoding]

    raise ValueError("Invalid encoding `%s` given" % key_encoding)