Add support for converting lottie stickers

Dockerfile.ci

@@ -1,10 +1,15 @@
+FROM dock.mau.dev/tulir/lottieconverter AS lottie
+
 FROM alpine:3.17
 
 ENV UID=1337 \
     GID=1337
 
-RUN apk add --no-cache ffmpeg su-exec ca-certificates bash jq curl yq
+RUN apk add --no-cache ffmpeg su-exec ca-certificates bash jq curl yq \
+    zlib libpng giflib libstdc++ libgcc
 
+COPY --from=lottie /usr/lib/librlottie.so* /usr/lib/
+COPY --from=lottie /usr/local/bin/lottieconverter /usr/local/bin/lottieconverter
 ARG EXECUTABLE=./mautrix-discord
 COPY $EXECUTABLE /usr/bin/mautrix-discord
 COPY ./example-config.yaml /opt/mautrix-discord/example-config.yaml