Fix parsing of the is_master attribute in the URL

[JackiLin]

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Description of change

Fixed the parsing of the is_master attribute in the Redis URL.
When the Redis URL is 'redis://redis-master/1?is_master=0', it is supposed to find the slave node of redis-master for read operations. However, since is_master was parsed as '0' and not correctly interpreted as False, it failed to use the slave node.
I encountered this issue when trying to implement read-write separation using SentinelConnectionPool.

[vladvildanov]

@JackiLin Thanks for you contribution! I would ask you to provide a test case

[JackiLin]

@JackiLin Thanks for you contribution! I would ask you to provide a test case

Is it OK to add test cases like this