Add changelog for v54

CHANGELOG.rst:
Add changelog entry for v54.
6 jobs for master in 42 minutes and 22 seconds (queued for 7 seconds)
Name Stage Failure
failed
build_long: [releng iso] Build
Running after script...
$ PROFILE=($BUILD_SCRIPT_ARGS) && cp -- "output/${PROFILE[0]}/metrics.txt" .
cp: cannot stat 'output/releng/metrics.txt': No such file or directory
Uploading artifacts for failed job
Uploading artifacts...
WARNING: metrics.txt: no matching files
ERROR: No files to upload
Cleaning up file based variables
ERROR: Job failed: exit code 1