patch sources

Author: tgross35

ci/docker/x86_64-unknown-linux-gnu/Dockerfile

@@ -1,5 +1,6 @@
-FROM ubuntu:25.10
+FROM ubuntu:24.10
 
+RUN sed -i -re 's/([a-z]{2}\.)?archive.ubuntu.com|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list
 RUN apt-get update
 RUN apt-get install -y --no-install-recommends \
   gcc g++ libc6-dev ca-certificates linux-headers-generic