Fix typo

.github/workflows/upload.yml

@@ -37,6 +37,6 @@ jobs:
           cd niclaurenti.github.io
           git config user.email "[email protected]"
           git config user.name "niclaurenti"
-          git add files/cqft_exercises.pdf
+          git add files/qft_exercises.pdf
           git commit -m "Automated update of qft_exercises.pdf: ${{ github.event.head_commit.message }}"
           git push