Fix typo in conflict check workflow

Missing `"` at the end of the string causes workflow failures.

I introduced this in 8d7fa6d but
I guess it never caused a problem till now...?

Author: ahpook

.github/workflows/conflict.yml

@@ -14,7 +14,7 @@ jobs:
       - run: |
           echo "In order to review this pull request for acceptance, we need to make sure that all of the prerequisites are satisfied."
           echo "This was not checked:"
-          echo "> This change is not self-promotion.
+          echo "> This change is not self-promotion."
           echo "This is a requirement to maintain a high level of independence in this project. Please update to confirm there is no conflict of interest."
           echo "Thank you!"
           exit 1