disable composer self-update due to a breaking change

Dockerfile

@@ -36,7 +36,11 @@ WORKDIR /data
 # Install/cleanup composer dependencies
 COPY composer.json /data/
 COPY composer.lock /data/
-RUN composer self-update --no-interaction
+# Disabled the self-update due to a breaking change between composer 2.6.6 and 2.7.1 that affects the loading
+# of the simplesamlphp/simplesamlphp/modules folder. The Docker build fails on the sildisco/sspoverrides line.
+# It is not well understood what changed in composer, but since the overrides will need to be redesigned during
+# the SimpleSAMLphp 2.x upgrade, this issue is deferred until then.
+#RUN composer self-update --no-interaction
 RUN composer install --prefer-dist --no-interaction --no-dev --optimize-autoloader --no-scripts --no-progress
 
 # Copy in SSP override files