feat(crypto): implement SHA-3 variants (sha3-224, sha3-256, sha3-384, sha3-512)

[LVivona]

Summary

Full support for sha3 python crypto module as suggested in #2 including implementations for SHA3-224, SHA3-256, SHA3-384, and SHA3-512. Provides a unified API for hashing and prepares the module for future extensibility. Closes #2.

Example

MrkleNode creation

from mrkle import MrkleNode

node = MrkleNode.leaf(b"hello world", name="sha3_224")

MrkleTree creation

from mrkle import MrkleTree

test = { "a" : { "b" : b"hello", "c" : b"world" } }
tree = MrkleTree.from_dict(test, name="sha3_224")