Include WebP runtime dependencies and avatar test painter

tools/chatgui/build_nix.sh

@@ -55,7 +55,7 @@ install_deps() {
     echo "[deps] installing build dependencies..."
     if [ "$OS_ID" = linux ]; then
         sudo apt-get update
-        sudo apt-get install -y build-essential cmake qt6-base-dev qt6-tools-dev-tools qt6-translations-l10n librlottie-dev zlib1g-dev libssl-dev \
+        sudo apt-get install -y build-essential cmake qt6-base-dev qt6-image-formats-plugins qt6-tools-dev-tools qt6-translations-l10n librlottie-dev zlib1g-dev libssl-dev \
             libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libswresample-dev
     else
         sudo pkg install -y cmake qt6-base qt6-tools qt6-translations rlottie openssl ffmpeg

tools/chatgui/tests/test_avatars.cpp

@@ -6,6 +6,7 @@
 #include <QTemporaryDir>
 #include <QFile>
 #include <QCryptographicHash>
+#include <QPainter>
 extern "C" {
 #include "utun_instance.h"
 #include "chat/chat_core.h"