CTestTestChecksum failing after CDash update

This test began failing on 2023-07-22 as shown here:

https://open.cdash.org/testSummary.php?project=1&name=CTestTestChecksum&date=2023-07-22

This was caused by an upgrade of open.cdash.org.

CDash now responds with HTTP 400 (bad request) rather than HTTP 200 (OK) for MD5 checksum mismatches during submission time.