fix(CI): Fix commit message check on single commit PRs

The range of COMMIT..COMMIT does not count the starting commit, so
single commit PRs are completely unchecked, and multi commit PRs don't
have their first commit checked.

.ci-scripts/verify-commit-format.sh

@@ -21,5 +21,5 @@ set -eu -o pipefail
 
 # Verify commit messages
 readarray -t COMMITS <<<$(curl -s ${GITHUB_CONTEXT} | jq -r '.[0,-1].sha')
-COMMIT_RANGE="${COMMITS[1]}..${COMMITS[0]}"
+COMMIT_RANGE="${COMMITS[1]}~1..${COMMITS[0]}"
 bash ./verify-commit-messages.sh "$COMMIT_RANGE"