docs: fix grammar in tests/byzantium (#47)

Fix inaccurate docstrings in test_gas.py files that incorrectly
listed precompiles not actually tested by each file.

Co-authored-by: Claude <noreply@anthropic.com>

Author: danceratopz

repo_subpaths_for_grammar_check.md

@@ -15,7 +15,7 @@ Status legend: `[ ]` pending, `[~]` in progress, `[x]` complete
 - [x] `tests/benchmark/**/*.py` (~36 files)
 - [x] `tests/json_infra/**/*.py` (~22 files)
 - [x] `tests/shanghai/**/*.py` (~19 files)
-- [ ] `tests/byzantium/**/*.py` (~11 files)
+- [x] `tests/byzantium/**/*.py` (~11 files)
 - [ ] `tests/istanbul/**/*.py`, `berlin/**/*.py` (~18 files)
 - [ ] `tests/constantinople/**/*.py`, `amsterdam/**/*.py` (~16 files)
 - [ ] `tests/london/**/*.py`, `homestead/**/*.py`, `paris/**/*.py` (~17 files)

tests/byzantium/eip196_ec_add_mul/test_gas.py

@@ -35,8 +35,7 @@ def test_gas_costs(
     enough_gas: bool,
 ) -> None:
     """
-    Tests the constant gas behavior of `ecadd/ecmul/ecpairing` precompiled
-    contract.
+    Tests the constant gas behavior of `ecadd/ecmul` precompiled contracts.
     """
     gas_costs = fork.gas_costs()
     gas = (

tests/byzantium/eip197_ec_pairing/test_gas.py

@@ -34,8 +34,7 @@ def test_gas_costs(
     enough_gas: bool,
 ) -> None:
     """
-    Tests the constant gas behavior of `ecadd/ecmul/ecpairing` precompiled
-    contract.
+    Tests the constant gas behavior of `ecpairing` precompiled contract.
     """
     gas = fork.gas_costs().G_PRECOMPILE_ECPAIRING_BASE
     if not enough_gas: