Fix Missing ClusterPipeline Lock

[grippy]

Pull Request check-list

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• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
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Description of change

This fixes this issue: #2189

A MOVED response from a cluster pipeline command might fail to initialize a new connection if the node hasn't been seen before. This causes a failure because ClusterPipeline never initializes its RedisCluster base class. Because of this we get an AttributeError while trying to use the _lock in the RedisCluster.get_redis_connection call.

[codecov-commenter]

Codecov Report

Merging #2190 (8b0f065) into master (9167a0e) will increase coverage by 12.64%.
The diff coverage is 66.66%.

@@             Coverage Diff             @@
##           master    #2190       +/-   ##
===========================================
+ Coverage   79.35%   91.99%   +12.64%     
===========================================
  Files         108      108               
  Lines       27372    27376        +4     
===========================================
+ Hits        21720    25185     +3465     
+ Misses       5652     2191     -3461     

Impacted Files	Coverage Δ
redis/commands/json/__init__.py	97.56% <ø> (ø)
redis/commands/timeseries/__init__.py	94.73% <ø> (ø)
redis/cluster.py	90.33% <66.66%> (+68.41%)	⬆️
tests/test_graph.py	90.68% <0.00%> (+0.03%)	⬆️
redis/commands/core.py	82.99% <0.00%> (+0.16%)	⬆️
redis/connection.py	86.36% <0.00%> (+0.47%)	⬆️
redis/client.py	88.76% <0.00%> (+0.76%)	⬆️
redis/commands/parser.py	67.77% <0.00%> (+1.11%)	⬆️
redis/asyncio/connection.py	83.85% <0.00%> (+1.68%)	⬆️
tests/test_scripting.py	93.67% <0.00%> (+3.16%)	⬆️
... and 11 more

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