CI FIX: Make sure setuptools_scm is installed for sdist building

There was a little snafu with the pypi upload for the new tag after switching to setuptool_scm. Due to a known issue with setuptools the code was tagged as v0.0.0.

The fix is to make sure setuptools_scm is installed in that job. I've run a test that the dist will build properly. I'll revert some of the CI changes when that passes.

(I manually pushed the tag with the correct label to pypi.)

.gitlab-ci.yml

@@ -289,7 +289,7 @@ pypi-release:
     TWINE_USERNAME: $PYPI_USERNAME
     TWINE_PASSWORD: $PYPI_PASSWORD
   before_script:
-    - pip install twine
+    - pip install twine setuptools_scm
     - python setup.py sdist
   script:
     - twine upload dist/*