CI: Add ffmpeg

.gitlab-ci.yml

@@ -59,7 +59,7 @@ unit-testing:
     alias: postgres
     command: ["postgres", "-c", "fsync=off", "-c", "synchronous_commit=off", "-c", "full_page_writes=off"]
   script:
-    - apt-get update && apt-get install -y libimage-exiftool-perl
+    - apt-get update && apt-get install -y libimage-exiftool-perl ffmpeg
     - mix deps.get
     - mix ecto.create
     - mix ecto.migrate
@@ -93,7 +93,7 @@ unit-testing-rum:
     <<: *global_variables
     RUM_ENABLED: "true"
   script:
-    - apt-get update && apt-get install -y libimage-exiftool-perl
+    - apt-get update && apt-get install -y libimage-exiftool-perl ffmpeg
     - mix deps.get
     - mix ecto.create
     - mix ecto.migrate