docker (e2e): add GStreamer dependencies to test WebRTC stack:

rel 424

docker/backend-dev-e2e/Dockerfile

@@ -19,7 +19,16 @@ RUN mkdir -m 777 /reports && \
     telnet net-tools \
     # needed to make Firefox trust system certificates
     # cf. https://askubuntu.com/a/1036637
-    p11-kit && \
+    p11-kit \
+    # GStreamer, used to test WebRTC stack
+    libgstreamer1.0-0 \
+    gstreamer1.0-plugins-base \
+    gstreamer1.0-plugins-good \
+    gstreamer1.0-plugins-bad \
+    gstreamer1.0-nice \
+    gir1.2-gstreamer-1.0 \
+    gir1.2-gst-plugins-bad-1.0 \
+    python3-gst-1.0 && \
     ln -fs /usr/lib/x86_64-linux-gnu/pkcs11/p11-kit-trust.so /usr/lib/firefox-esr/libnssckbi.so
 
 # we install pre-generated certificates so we can do tests with valid TLS