test-your-pr: fix bot comment: properties/body [skip ci]

Signed-off-by: Jerry <[email protected]>

.github/workflows/test-your-pr.yml

@@ -97,7 +97,7 @@ jobs:
               issue_number: context.issue.number,
               owner: context.repo.owner,
               repo: context.repo.repo,
-              body: fs.readFileSync('/tmp/buildjob_tail.log')
+              body: fs.readFileSync('/tmp/buildjob_tail.log', { encoding: 'utf8', flag: 'r' })
             })
 
       - run: false