You're able to install and run sentry-cli from inside the post-xcodebuild script.
This was working for me (you can define the SENTRY_AUTH_TOKEN as an environment value in the workflow):
ci_scripts/ci_post_xcodebuild.sh
#!/bin/sh
set -e
# This is necessary in order to have sentry-cli
# install locally into the current directory
export INSTALL_DIR=$PWD
if [[ $(command -v sentry-cli) == "" ]]; then
echo "Installing Sentry CLI"
curl -sL https://sentry.io/get-cli/ | bash
fi
echo "Uploading dSYM to Sentry"
sentry-cli --auth-token $SENTRY_AUTH_TOKEN \
upload-dif --org 'organization-name' \
--project 'project-name' \
$CI_ARCHIVE_PATH