Switching %r for repr(op_str) in test-expressions.py for issue 29886
Swaps the following in pandas/tests/test_expressions.py:
From:
    `msg = "operator %r not implemented for bool dtypes"`
    `f = getattr(operator, opname)`
    `err_msg = re.escape(msg % op_str)`
To:
    `msg = f"operator {repr(op_str)} not implemented for bool dtypes"`
    `f = getattr(operator, opname)`
    `err_msg = re.escape(msg)`

This is for [#29886](https://github.com/pandas-dev/pandas/issues/29886)