2015 typo to 2025.
The SPDX_HEADER constant was changed to the STAMP constant and the SPDX_HEADER is now "// SPDX-License-Identifier:".
This was a quickly written tool to add the SPDX license header to all the *.rs files. It just checks if the license is at the top. If it isn't it stamps the file. If it is it ignores it.
