upgrade golangci to v2

* migrate configuration to version 2
* fix new lint warnings
* update lint.yaml to use golangci-lint-action v7

pkg/bytepool/bytepool.go

@@ -11,7 +11,7 @@ type BytePool struct {
 // NewBytePool allocates a new BytePool with slices of equal length and capacity.
 func NewBytePool(length int) *BytePool {
 	var bp BytePool
-	bp.Pool.New = func() any {
+	bp.New = func() any {
 		// This avoids allocations for the slice metadata, see:
 		// https://staticcheck.io/docs/checks#SA6002
 		b := make([]byte, length)