include SPDX-License on AssertBytes32.sol
include SPDX-License on AssertBytes32.sol

Getting a warning message when using the most recent compiler

"  truffle/AssertBytes32.sol: Warning: SPDX license identifier not provided in source file. Before publishing, consider adding a comment containing "SPDX-License-Identifier: <SPDX-License>" to each source file. Use "SPDX-License-Identifier: UNLICENSED" for non-open-source codeontaining "SPDX-License-Identifier: <SPDX-License>" to each so. Please see https://spdx.org for more information."
ConsenSys/truffle