build(deps): Bump redis from 3.2.1 to 3.3.0 in /backend

[dependabot-preview]

Bumps redis from 3.2.1 to 3.3.0.

Changelog

Sourced from redis's changelog.

• 3.3.0
  • Resolve a race condition with the PubSubWorkerThread. #1150
  • Cleanup socket read error messages. Thanks Vic Yu. #1159
  • Cleanup the Connection's selector correctly. Thanks Bruce Merry. #1153
  • Added a Monitor object to make working with MONITOR output easy.
    Thanks Roey Prat #1033
  • Internal cleanup: Removed the legacy Token class which was necessary
    with older version of Python that are no longer supported. #1066
  • Response callbacks are now case insensitive. This allows users that
    call Redis.execute_command() directly to pass lower-case command
    names and still get reasonable respones. #1168
  • Added support for hiredis-py 1.0.0 encoding error support. This should
    make the PythonParser and the HiredisParser behave identically
    when encountering encoding errors. Thanks Brian Candler. #1161/#1162
  • All authentication errors now properly raise AuthenticationError.
    AuthenticationError is now a subclass of ConnectionError, which will
    cause the connection to be disconnected and cleaned up appropriately.
    #923
  • Add READONLY and READWRITE commands. Thanks @​theodesp. #1114
  • Remove selectors in favor of nonblocking sockets. Selectors had
    issues in some environments including eventlet and gevent. This should
    resolve those issues with no other side effects.
  • Fixed an issue with XCLAIM and previously claimed but not removed
    messages. Thanks @​thomdask. #1192/#1191
  • Allow for single connection client instances. These instances
    are not thread safe but offer other benefits including a subtle
    performance increase.
  • Added extensive health checks that keep the connections lively.
    Passing the "health_check_interval=N" option to the Redis client class
    or to a ConnectionPool ensures that a round trip PING/PONG is successful
    before any command if the underlying connection has been idle for more
    than N seconds. ConnectionErrors and TimeoutErrors are automatically
    retried once for health checks.
  • Changed the PubSubWorkerThread to use a threading.Event object rather
    than a boolean to control the thread's life cycle. Thanks Timothy
    Rule. #1194/#1195.
  • Fixed a bug in Pipeline error handling that would incorrectly retry
    ConnectionErrors.

Commits

• 0de7c82 clearer language in docs
• d9227fe update readme with health_check_interval option
• 06b6113 version 3.3.0
• 9e4c1ff Pipelines shouldn't retry ConnectionErrors implicitly
• 6ce11f1 Add an Event parameter to PubSubWorkerThread and run_in_thread so (#1195)
• f60b2b0 PING/PONG health checks
• 0984b10 Ability to create a client that uses a single connection
• 6e23760 Fix typo in README and CHANGELOG (#1133)
• 088c0ab Updates README.rst with svg badge (#1182)
• 5faed95 Handle removed claimed messages without an exception
• Additional commits viewable in compare view

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[dependabot-preview]

Superseded by #86.