Release v1.21.0

What's Changed

• Shorten cmake test names so they fit in GitHub by @andrewhop in #1394
• Turn off flaky MariaDB test main.ssl_crl by @andrewhop in #1396
• Update all integration targets to use RelWithDebInfo and increase size of ARM OpenSSH test host by @andrewhop in #1393
• Update base ec2 test framework by @andrewhop in #1395
• Use system allocator for thread-local values by @justsmth in #1397
• Implement AES-CCM by @geedo0 in #1373
• Upstream merge 2024 01 05 by @justsmth in #1385
• Implement SSL_MODE_AUTO_RETRY by @WillChilds-Klein in #1333
• Turn off Graviton 3 test by @andrewhop in #1399
• temporarily turn off 32-bit Windows SDE CI by @samuel40791765 in #1406
• allow HMAC via EVP_PKEY raw privkey functions by @samuel40791765 in #1338
• Only build the grpc tests that we're going to run to save time by @andrewhop in #1412
• Update CDK docs/dependencies by @justsmth in #1392
• Update Formal Verification section in README to match latest status by @pennyannn in #1413
• Upstream merge 2024 01 12 by @andrewhop in #1402
• Skip another MariaDB test that appears to be flaky. P112867839 by @andrewhop in #1411
• Integration with tpm2-tss by @justsmth in #1361
• Fix issue with iOS FIPS builds. Requires -DCMAKE_SYSTEM_NAME=iOS by @skmcgrail in #1416
• Add socat integration test by @andrewhop in #1387
• Use standard CMake options to specify C/C++ language standard, add BoringSSL to speed test by @andrewhop in #1410
• Upstream merge 2024 01 17 by @skmcgrail in #1414
• More test coverage for AWSLC_thread_local_clear by @justsmth in #1409
• Staging v1.21.0 release by @torben-hansen in #1421

Full Changelog: v1.20.0...v1.21.0