CI fix

Now using an up to date container with ACTs.

modified: .gitlab-ci.yml modified: bin/do_build modified: src/GenericDetectors/pid/README.md

bin/do_build

@@ -6,4 +6,4 @@ source /usr/local/bin/geant4.sh
 mkdir build
 cd build
 cmake ../. -DCMAKE_INSTALL_PREFIX=/usr/local
-make -j10
+make -j20