[#1341] .golangci.yml: Replace exportloopref with copyloopvar

exportloopref is deprecated.
gopatch:
```
@@
var index, value identifier
var slice expression
@@
for index, value := range slice {
...
-value := value
...
}

@@
var index, value identifier
var slice expression
@@
for index, value := range slice {
...
-index := index
...
}

@@
var value identifier
var channel expression
@@
for value := range channel {
...
-value := value
...
}
```

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/local_object_storage/engine/writecache.go

@@ -102,7 +102,6 @@ func (e *StorageEngine) SealWriteCache(ctx context.Context, prm SealWriteCachePr
 
 	eg, egCtx := errgroup.WithContext(ctx)
 	for _, shardID := range prm.ShardIDs {
-		shardID := shardID
 		eg.Go(func() error {
 			e.mtx.RLock()
 			sh, ok := e.shards[shardID.String()]