Use Nextflow 20.01.0 for CI

.gitlab-ci.yml

@@ -2,7 +2,7 @@ before_script:
   - module load astrocyte
   - module load python/3.6.1-2-anaconda
   - pip install --user pytest-pythonpath==0.7.1 pytest-cov==2.5.1
-  - module load nextflow/19.09.0
+  - module load nextflow/20.01.0
   - module load singularity/3.0.2
   - mkdir -p test_data/simple1
   - mkdir -p test_data/simple2