Gitlab ci

Add pytest-workflow tests and enable gitlab-ci integration, including the slurm runner.

test/config/config-GIAB-chrM.json

+{
+  "samples": {
+    "16699289": {
+      "disease_code": "TEST",
+      "gvcf": "test/data/16699289_chrM.g.vcf",
+      "vcf": "test/data/16699289_chrM.vcf"
+    }
+  }
+}