Data race on GetNextConnection in round-robin

[sku4]

Data race appear on nextIndex
As solution you can set mutex on Lock instead RLock
Thanks

==================
WARNING: DATA RACE
Read at 0x00c0001d8ae0 by goroutine 41:
github.com/tarantool/go-tarantool/v2/pool.(*roundRobinStrategy).nextIndex()
/Users/s.skubach/go/pkg/mod/github.com/tarantool/go-tarantool/v2@v2.0.0-20230614085627-6cddcd71029d/pool/round_robin.go:107 +0x4c
github.com/tarantool/go-tarantool/v2/pool.(*roundRobinStrategy).GetNextConnection()
/Users/s.skubach/go/pkg/mod/github.com/tarantool/go-tarantool/v2@v2.0.0-20230614085627-6cddcd71029d/pool/round_robin.go:80 +0x1b5
github.com/tarantool/go-tarantool/v2/pool.(*ConnectionPool).getNextConnection()
/Users/s.skubach/go/pkg/mod/github.com/tarantool/go-tarantool/v2@v2.0.0-20230614085627-6cddcd71029d/pool/connection_pool.go:1261 +0x25d
github.com/tarantool/go-tarantool/v2/pool.(*ConnectionPool).CallTyped()
/Users/s.skubach/go/pkg/mod/github.com/tarantool/go-tarantool/v2@v2.0.0-20230614085627-6cddcd71029d/pool/connection_pool.go:564 +0xb1

[oleg-jukovec]

Thank you for the issue, I've created the fix: #312

The problem is not too critical: it should not lead to crashes. But a request can be sent to the same connection several times in a row.