Use a tmp patched gst-libav to cope with decoding deadlock, fixes #37552

The patch will be available on GStreamer 1.22.2

Dockerfile

@@ -9,10 +9,14 @@ RUN \
     pacman -S archlinux-keyring --noconfirm --noprogressbar --quiet --needed && \
     pacman -Su --noconfirm --noprogressbar --quiet && \
     pacman -S --noconfirm --noprogressbar --quiet --needed \
-        git vim \
-        gstreamer gst-plugins-base gst-plugins-good gst-plugins-bad gst-plugins-ugly gst-libav \
+        git vim curl \
         qrencode zbar make \
-        python-setuptools python-pip python-gobject gst-python python-numpy
+        python-setuptools python-pip python-gobject python-numpy
+
+# FFmpeg6 with Gst 1.22 is racy see https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/238, so we need a patched version of gst-libav until Gst 1.22.2
+RUN curl -O https://nextcloud.ubicast.net/s/YyjoCzgpPTYr67j/download/gst-libav-1.22.1-2-x86_64.pkg.tar.zst
+RUN pacman -U --noconfirm gst-libav-1.22.1-2-x86_64.pkg.tar.zst
+RUN pacman -S --noconfirm --noprogressbar --quiet --needed gstreamer gst-plugins-base gst-plugins-good gst-plugins-bad gst-plugins-ugly gst-libav gst-python
 
 COPY . /opt/qrlipsync