upgrade nydus version to v2.3.0 in test

[imeoer]

nydus v2.3.0 released: https://github.com/dragonflyoss/nydus/releases/tag/v2.3.0

[Desiki-high]

Need to update the chunkmap suffix:

nydus-snapshotter/tests/converter_test.go

Lines 525 to 528 in d6ca59c

	ensureFile(t, filepath.Join(cacheDir, chunkDictBlobHash)+".chunk_map")
	ensureNoFile(t, filepath.Join(cacheDir, lowerNydusBlobDigest.Hex())+".chunk_map")
	ensureFile(t, filepath.Join(cacheDir, upperNydusBlobDigest.Hex())+".chunk_map")
	}