Remove unused code

tests/test_core.py

 import pytest
-from openpyxl import Workbook
 from validata_core import validate
 from validata_core.helpers import FileContentValidataResource, ValidataSourceError
 
@@ -157,20 +156,3 @@ def test_disordered_columns(schema_abc):
     assert (
         report["tasks"][0]["structure_warnings"][0]["code"] == "disordered-header-warn"
     )
-
-
-# XLSX
-
-
-def validate_xlsx_bytes(bytes_source_content, schema):
-    validata_source = FileContentValidataResource("foo.xlsx", bytes_source_content)
-    header, rows = validata_source.extract_tabular_data()
-    return validate([header] + rows, schema)
-
-
-def build_one_cell_xlsx(cell):
-    wb = Workbook()
-    ws1 = wb.active
-    ws1["A1"] = "A"
-    ws1["A2"] = cell
-    return wb