Update dependency black to v26

Author: renovate[bot]

pyproject.toml

@@ -56,7 +56,7 @@ Changelog = "https://github.com/SAP/invoke-plugin-for-sphinx/blob/main/CHANGELOG
 dev = [
     "pre-commit==4.5.1",
     "pylint==4.0.4",
-    "black==25.12.0",
+    "black==26.1.0",
     "isort==7.0.0",
     "mypy==1.19.1",
     "types-invoke==2.0.0.10",