Revert "restrict singularity builds to new version tags"

This reverts commit 7c7656cf.

.gitlab-ci.yml

@@ -91,6 +91,7 @@ build-singularity:
     entrypoint: [""]
   stage: deploy
   only:
+    - master
     - tags
   script:
     - echo $sylabstoken  > SYLABS_TOKEN_FILE
@@ -106,5 +107,6 @@ publish:
     - python setup.py sdist bdist_wheel
     - twine upload --username $PYPI_USERNAME --password $PYPI_PASSWORD --verbose dist/*
   only:
-    - tags
+      - tags
+      - master
   interruptible: true