Include link to the SHA being cherry-picked.

Author: desrosj

.github/workflows/backport.yml

@@ -239,7 +239,7 @@ jobs:
           fi
 
           if [ -n "${INPUTS_COMMIT_SHA}" ]; then
-            BODY="This pull request backports \`${INPUTS_COMMIT_SHA}\` to the \`${MATRIX_BRANCH}\` branch."
+            BODY="This pull request backports \`${INPUTS_COMMIT_SHA}\` (https://github.com/${STEPS_UPSTREAM_OUTPUTS_REPO}/commit/${INPUTS_COMMIT_SHA}) to the \`${MATRIX_BRANCH}\` branch."
           else
             BODY="Backport to the \`${MATRIX_BRANCH}\` branch."
           fi