fix(docker): Debian Bullseye Archive-Repositories fuer Paketinstallation nutzen

Dockerfile

@@ -5,6 +5,11 @@ RUN mkdir /opt/tmserver
 WORKDIR /opt/tmserver
 
 # Alle benoetigten Pakete in einem Layer installieren und Cache aufraeumen
+# Debian Bullseye Archive-Repositories konfigurieren (Bullseye ist archiviert)
+RUN echo "deb http://archive.debian.org/debian bullseye main" > /etc/apt/sources.list \
+    && echo "deb http://archive.debian.org/debian-security bullseye-security main" >> /etc/apt/sources.list \
+    && echo "Acquire::Check-Valid-Until false;" > /etc/apt/apt.conf.d/99no-check-valid-until
+
 RUN apt-get update && apt-get install -y --no-install-recommends \
     unzip \
     apache2 \