[BUG] ipmi.get_health: NameError: name 'unicode' is not defined

Description
The get_health method of the ipmi module throws NameError: name 'unicode' is not defined when querying my SuperMicro IPMI.

[root@salt ~]# salt 'uslogsdnas01.--redacted--.local' ipmi.get_health api_host=--redacted-ip-- api_user='admin' api_pass='--redacted-password--'
uslogsdnas01.--redacted--.local:
    The minion function caused an exception: Traceback (most recent call last):
      File "/usr/lib/python3/dist-packages/salt/minion.py", line 1905, in _thread_return
        function_name, function_args, executors, opts, data
      File "/usr/lib/python3/dist-packages/salt/minion.py", line 1861, in _execute_job_function
        return_data = self.executors[fname](opts, data, func, args, kwargs)
      File "/usr/lib/python3/dist-packages/salt/loader.py", line 1241, in __call__
        return self.loader.run(run_func, *args, **kwargs)
      File "/usr/lib/python3/dist-packages/salt/loader.py", line 2274, in run
        return self._last_context.run(self._run_as, _func_or_method, *args, **kwargs)
      File "/usr/lib/python3/dist-packages/salt/loader.py", line 2289, in _run_as
        return _func_or_method(*args, **kwargs)
      File "/usr/lib/python3/dist-packages/salt/executors/direct_call.py", line 12, in execute
        return func(*args, **kwargs)
      File "/usr/lib/python3/dist-packages/salt/loader.py", line 1241, in __call__
        return self.loader.run(run_func, *args, **kwargs)
      File "/usr/lib/python3/dist-packages/salt/loader.py", line 2274, in run
        return self._last_context.run(self._run_as, _func_or_method, *args, **kwargs)
      File "/usr/lib/python3/dist-packages/salt/loader.py", line 2289, in _run_as
        return _func_or_method(*args, **kwargs)
      File "/usr/lib/python3/dist-packages/salt/modules/ipmi.py", line 611, in get_health
        return s.get_health()
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/command.py", line 660, in get_health
        for reading in self.get_sensor_data():
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/command.py", line 858, in get_sensor_data
        self._sdr = sdr.SDR(self)
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/sdr.py", line 610, in __init__
        self.read_info()
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/sdr.py", line 641, in read_info
        self.get_sdr()
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/sdr.py", line 715, in get_sdr
        self.add_sdr(sdrdata)
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/sdr.py", line 734, in add_sdr
        newent = SDREntry(sdrbytes, self.ipmicmd)
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/sdr.py", line 276, in __init__
        self.fru_decode(entrybytes[5:])
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/sdr.py", line 310, in fru_decode
        self.fru_name = self.tlv_decode(entry[10], entry[11:])
      File "/usr/lib/python3/dist-packages/pyghmi/ipmi/sdr.py", line 575, in tlv_decode
        return unicode(struct.pack("%dB" % len(data), *data), "utf_8")
    NameError: name 'unicode' is not defined

Versions Report
Minion:

    Salt Version:
              Salt: 3003.2
     
    Dependency Versions:
              cffi: Not Installed
          cherrypy: Not Installed
          dateutil: 2.7.3
         docker-py: Not Installed
             gitdb: Not Installed
         gitpython: Not Installed
            Jinja2: 2.10
           libgit2: Not Installed
          M2Crypto: 0.31.0
              Mako: Not Installed
           msgpack: 0.5.6
      msgpack-pure: Not Installed
      mysql-python: Not Installed
         pycparser: Not Installed
          pycrypto: 2.6.1
      pycryptodome: 3.6.1
            pygit2: Not Installed
            Python: 3.7.3 (default, Jan 22 2021, 20:04:44)
      python-gnupg: Not Installed
            PyYAML: 3.13
             PyZMQ: 17.1.2
             smmap: Not Installed
           timelib: Not Installed
           Tornado: 4.5.3
               ZMQ: 4.3.1
     
    System Versions:
              dist: debian 10 buster
            locale: UTF-8
           machine: x86_64
           release: 5.4.128-1-pve
            system: Linux
           version: Debian GNU/Linux 10 buster

Start with salt/modules/ipmi.py at get_health, then follow the traceback into pyghmi/ipmi/sdr.py and its tlv_decode path. Reproduce the SuperMicro get_health call or inspect the reported Python 3 failure. Done means the IPMI health query completes without the reported NameError for the affected response.