README: add reuse compliance badge

Author: fvalette-ledger

README.md

@@ -4,6 +4,8 @@ SPDX-FileCopyrightText: 2024 Ledger SAS
 SPDX-License-Identifier: Apache-2.0
 -->
 
+[![REUSE status](https://api.reuse.software/badge/github.com/outpost-os/python-dts-utils)](https://api.reuse.software/info/github.com/outpost-os/python-dts-utils)
+
 # dts-utils python package
 `dts-utils` is an utility python package that aims to ease dts handling in python and source code
 generation based on dts files. Dts file parsing, preprocessing, validation are **out of scope** of