fix bigfoot docker

Linux/BigfootBuilder/Dockerfile

@@ -15,7 +15,9 @@ RUN apt-get update \
         xvfb \
     \
     # LunarG Vulkan repo (modern keyring method)
-    && wget -qO /usr/share/keyrings/lunarg-archive-keyring.gpg https://packages.lunarg.com/lunarg-signing-key-pub.asc; \
+    && wget -qO- https://packages.lunarg.com/lunarg-signing-key-pub.asc \
+      | gpg --dearmor -o /usr/share/keyrings/lunarg-archive-keyring.gpg \
+    \
     && echo "deb [signed-by=/usr/share/keyrings/lunarg-archive-keyring.gpg] https://packages.lunarg.com/vulkan/1.4.313 noble main" \
         > /etc/apt/sources.list.d/lunarg-vulkan.list \
     \