pyproject.toml: Fix deprecation warning (MR 2262)

Fixes this warning:

warning: The top-level linter settings are deprecated in favour of their counterparts in the `lint` section. Please update the following options in `pyproject.toml`:
  - 'ignore' -> 'lint.ignore'

pyproject.toml

@@ -31,5 +31,5 @@ exclude = ["aports", "keys", "test", "test.pmb_test"]
 [tool.ruff]
 # E402: module import not on top of file, not possible for testcases
 # E722: do not use bare except
-ignore=["E402", "E722"]
+lint.ignore=["E402", "E722"]
 line-length=100