remove `BLOB_TX_TYPE` from spec (and move to tests)

specs/deneb/beacon-chain.md

@@ -77,7 +77,6 @@ Deneb is a consensus-layer upgrade containing a number of features. Including:
 
 | Name | Value |
 | - | - |
-| `BLOB_TX_TYPE` | `uint8(0x03)` |
 | `VERSIONED_HASH_VERSION_KZG` | `Bytes1('0x01')` |
 
 ## Preset

tests/core/pyspec/eth2spec/test/helpers/sharding.py

@@ -7,6 +7,7 @@ from eth2spec.utils.ssz.ssz_typing import (
     Union,
     boolean,
     uint256, uint64,
+    uint8,
 )
 from eth2spec.utils.ssz.ssz_impl import serialize
 
@@ -20,6 +21,9 @@ MAX_ACCESS_LIST_STORAGE_KEYS = 2**24
 MAX_ACCESS_LIST_SIZE = 2**24
 
 
+BLOB_TX_TYPE = uint8(0x03)
+
+
 class AccessTuple(Container):
     address: Bytes20  # Address = Bytes20
     storage_keys: List[Bytes32, MAX_ACCESS_LIST_STORAGE_KEYS]
@@ -120,5 +124,5 @@ def get_sample_opaque_tx(spec, blob_count=1, rng=random.Random(5566), is_valid_b
         )
     )
     serialized_tx = serialize(signed_blob_tx)
-    opaque_tx = spec.uint_to_bytes(spec.BLOB_TX_TYPE) + serialized_tx
+    opaque_tx = spec.uint_to_bytes(BLOB_TX_TYPE) + serialized_tx
     return opaque_tx, blobs, blob_kzg_commitments, blob_kzg_proofs