update the badges link in README.md

[coveralls]

Pull Request Test Coverage Report for Build 8430357145

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 24 unchanged lines in 9 files lost coverage.
• Overall coverage increased (+0.05%) to 66.865%

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Files with Coverage Reduction	New Missed Lines	%
com/baidu/bifromq/basecluster/memberlist/AutoSeeder.java	1	84.43%
com/baidu/bifromq/inbox/server/InboxService.java	2	79.68%
com/baidu/bifromq/basecluster/fd/FailureDetector.java	2	89.8%
com/baidu/bifromq/basekv/raft/RaftNodeStateLeader.java	2	87.0%
com/baidu/bifromq/basekv/client/scheduler/BatchQueryCall.java	2	71.76%
com/baidu/bifromq/basekv/store/range/KVRangeFSM.java	2	78.57%
com/baidu/bifromq/basekv/raft/exception/LeaderTransferException.java	3	76.92%
com/baidu/bifromq/basecluster/transport/TCPTransport.java	4	86.93%
com/baidu/bifromq/basekv/raft/RaftNodeState.java	6	91.3%
<!--	Total:	24		-->

Totals
Change from base Build 8414634672:	0.05%
Covered Lines:	20897
Relevant Lines:	30415

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💛 - Coveralls