tests: add ffmpeg installation step to lint workflow

.github/workflows/lint.yml

@@ -20,6 +20,9 @@ jobs:
         with:
           go-version: ^1.23
 
+      - name: Install ffmpeg
+        run: sudo apt-get update && sudo apt-get install -y ffmpeg
+
       # When you execute your unit tests, make sure to use the "-coverprofile" flag to write a
       # coverage profile to a file. You will need the name of the file (e.g. "coverage.txt")
       # in the next step as well as the next job.