eip-7918: update blob_base_cost (#1915)

Author: gurukamath

docs/CHANGELOG.md

@@ -127,7 +127,7 @@ Users can select any of the artifacts depending on their testing needs for their
 - ✨ Introduce blockchain tests for benchmark to cover the scenario of pure ether transfers [#1742](https://github.com/ethereum/execution-spec-tests/pull/1742).
 - ✨ [EIP-7934](https://eips.ethereum.org/EIPS/eip-7934): Add test cases for the block RLP max limit of 10MiB ([#1730](https://github.com/ethereum/execution-spec-tests/pull/1730)).
 - ✨ [EIP-7939](https://eips.ethereum.org/EIPS/eip-7939) Add count leading zeros (CLZ) opcode tests for Osaka ([#1733](https://github.com/ethereum/execution-spec-tests/pull/1733)).
-- ✨ [EIP-7918](https://eips.ethereum.org/EIPS/eip-7918): Blob base fee bounded by execution cost test cases (initial), includes some adjustments to [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844) tests ([#1685](https://github.com/ethereum/execution-spec-tests/pull/1685)).
+- ✨ [EIP-7918](https://eips.ethereum.org/EIPS/eip-7918): Blob base fee bounded by execution cost test cases (initial), includes some adjustments to [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844) tests ([#1685](https://github.com/ethereum/execution-spec-tests/pull/1685)). Update the blob_base_cost ([#1915](https://github.com/ethereum/EIPs/pull/1915)).
 
 ## [v4.5.0](https://github.com/ethereum/execution-spec-tests/releases/tag/v4.5.0) - 2025-05-14
 

src/ethereum_test_forks/forks/forks.py

@@ -1479,7 +1479,7 @@ def excess_blob_gas_calculator(
         blob_gas_per_blob = cls.blob_gas_per_blob(block_number, timestamp)
         target_blob_gas_per_block = target_blobs_per_block * blob_gas_per_blob
         max_blobs_per_block = cls.max_blobs_per_block(block_number, timestamp)
-        blob_base_cost = 2**14  # EIP-7918 new parameter
+        blob_base_cost = 2**13  # EIP-7918 new parameter
 
         def fn(
             *,