Improve listing changed files in a commit

We ended up with revision 3b21550 for
several Tasks in the acceptable bundles, seems that the `git log` method
was also listing the files that were brought in by merging the main
branch onto the pull request branch.

This switches to using GitHub CLI to search for a merged pull request
that contains the top commit (`$REVISION`), and then lists the changed
files in that pull request.

This should contain only the list of files that were changed in the pull
request and not any changed files in a merge commit.

Reference: https://issues.redhat.com/browse/EC-1015

Author: zregvart

.tekton/scripts/build-acceptable-bundles.sh

@@ -7,10 +7,14 @@ set -o pipefail
 DATA_BUNDLE_REPO="${DATA_BUNDLE_REPO:-quay.io/konflux-ci/tekton-catalog/data-acceptable-bundles}"
 mapfile -t BUNDLES < <(cat "$@")
 
+pr_number=$(gh search prs --repo konflux-ci/build-definitions --merged "${REVISION}" --json number --jq '.[].number')
+
+# changed files in a PR
+mapfile -t changed_files < <(gh pr view "https://github.com/konflux-ci/build-definitions/pull/${pr_number}" --json files --jq '.files.[].path')
 # store a list of changed task files
 task_records=()
 # loop over all changed files
-for path in $(git log -m -1 --name-only --pretty="format:" "${REVISION}"); do
+for path in "${changed_files[@]}"; do
     # check that the file modified is the task file
     if [[ "${path}" == task/*/*/*.yaml ]]; then
         IFS='/' read -r -a path_array <<< "${path}"
@@ -30,6 +34,11 @@ printf '%s\n' "${task_records[@]}"
 echo "Bundles to be added:"
 printf '%s\n' "${BUNDLES[@]}"
 
+if [[ -z ${task_records[*]} && -z ${BUNDLES[*]} ]]; then
+    echo Nothing to do...
+    exit 0
+fi
+
 # The OPA data bundle is tagged with the current timestamp. This has two main
 # advantages. First, it prevents the image from accidentally not having any tags,
 # and getting garbage collected. Second, it helps us create a timeline of the