[build] Add `cffi` as a dependency for `yt_dlp_linux`

Closes #6394
Authored by: bashonly

.github/workflows/build.yml

@@ -100,8 +100,13 @@ jobs:
           python -m pip install -U pip setuptools wheel
           python -m pip install -U Pyinstaller -r requirements.txt
           reqs=$(mktemp)
-          echo -e 'python=3.10.*\npyinstaller' >$reqs
-          sed 's/^brotli.*/brotli-python/' <requirements.txt >>$reqs
+          cat > $reqs << EOF
+          python=3.10.*
+          pyinstaller
+          cffi
+          brotli-python
+          EOF
+          sed '/^brotli.*/d' requirements.txt >> $reqs
           mamba create -n build --file $reqs
 
       - name: Prepare