Try and set singularity cache for ci

.gitlab-ci.yml

@@ -2,6 +2,7 @@ before_script:
   - module load python/3.6.4-anaconda
   - pip install --user  attrs==19.1.0 pytest-pythonpath==0.7.1 pytest-cov==2.5.1 deriva==1.3.0
   - module load singularity/3.5.3
+  - export SINGULARITY_CACHE=/project/BICF/BICF_Core/shared/gudmap/singularity_cache
   - module load nextflow/20.01.0
   - ln -sfn /project/BICF/BICF_Core/shared/gudmap/test_data/* ./test_data/
   - mkdir -p ~/.deriva