Unset error exit around R pkg install

The install script throws unexpected warnings about being unable to
install arrow, even though arrow is already installed by conda.

build/hpc_install.sh

@@ -76,7 +76,10 @@ conda activate $USERDIR/flepimop-env
 pip install --force-reinstall $FLEPI_PATH/flepimop/gempyor_pkg
 
 # Install the local R packages
+set +e
 $FLEPI_PATH/build/setup.R $FLEPI_PATH
+set -e
 
 # Out source to flepi init for per run setup
 source $FLEPI_PATH/build/flepi_init.sh $1
+set +e