Update snappy to prevent crash on Apple M1

[yperbasis]

Pull in golang/snappy#56

I experienced a crash on Apple M1:

INFO [02-05|15:31:30.077] [1/14 Headers] Imported new block headers count=8040  elapsed=118.406ms number=6512640 hash="381d35…e5de60" age=2y4mo5d
unexpected fault address 0xaa5b45a7af6e024c
fatal error: fault
[signal SIGSEGV: segmentation violation code=0x2 addr=0xaa5b45a7af6e024c pc=0x1045f7050]

goroutine 30042 [running]:
runtime.throw(0x104c2ff01, 0x5)
	runtime/panic.go:1117 +0x54 fp=0x4400c4f0960 sp=0x4400c4f0930 pc=0x1040b9b14
runtime.sigpanic()
	runtime/signal_unix.go:741 +0x230 fp=0x4400c4f09a0 sp=0x4400c4f0960 pc=0x1040d1470
github.com/golang/snappy.encodeBlock(0x4400c59e003, 0x1d094, 0x1d094, 0x4400c546000, 0x10000, 0x1fe00, 0x14001674d00)
	github.com/golang/[email protected]/encode_arm64.s:666 +0x360 fp=0x4400c4f8a40 sp=0x4400c4f09b0 pc=0x1045f7050
github.com/golang/snappy.Encode(0x4400c59e000, 0x1d097, 0x1d097, 0x4400c556000, 0x8e1d, 0xfe00, 0x0, 0x1048b3864, 0x4400519eaf8)
	github.com/golang/[email protected]/encode.go:39 +0x17c fp=0x4400c4f8a90 sp=0x4400c4f8a40 pc=0x1045f658c
github.com/ledgerwatch/turbo-geth/p2p/rlpx.(*Conn).Write(0x14000e729c0, 0x14, 0x4400c546000, 0x18e1d, 0x1fe00, 0x0, 0x10591a6c0, 0x0)
	github.com/ledgerwatch/turbo-geth/p2p/rlpx/rlpx.go:185 +0xfc fp=0x4400c4f8af0 sp=0x4400c4f8a90 pc=0x1048a202c