Fix the issue of exiting due to inability to find hyperlinks (opea-project#929)

Signed-off-by: ZePan110 <ze.pan@intel.com>

Author: ZePan110

.github/workflows/pr-path-detection.yml

@@ -59,10 +59,10 @@ jobs:
           fail="FALSE"
           merged_commit=$(git log -1 --format='%H')
           changed_files="$(git diff --name-status --diff-filter=ARM ${{ github.event.pull_request.base.sha }} ${merged_commit} | awk '/\.md$/ {print $NF}')"
-          if  [ -n "changed_files" ]; then
+          if  [ -n "$changed_files" ]; then
             for changed_file in $changed_files; do
               echo $changed_file
-              url_lines=$(grep -H -Eo '\]\(http[s]?://[^)]+\)' "$changed_file" | grep -Ev 'GenAIExamples/blob/main')
+              url_lines=$(grep -H -Eo '\]\(http[s]?://[^)]+\)' "$changed_file" | grep -Ev 'GenAIExamples/blob/main') || true
               if [ -n "$url_lines" ]; then
                 for url_line in $url_lines; do
                   echo $url_line