Add a tox test using twine to check the setup.py metadata

.gitlab-ci.yml

@@ -56,4 +56,4 @@ test_lint:
   before_script:
     - pip install tox
   script:
-    - tox -e flake8,reuse
+    - tox -e flake8,reuse,twine

tox.ini

@@ -7,7 +7,7 @@
 # List Python 3.7 by default as that is the version installed on Debian 10
 # Developers on other systems should set the TOXENV environment
 # variable to the Python versions on their system
-envlist = py37,flake8,reuse
+envlist = py37,flake8,reuse,twine
 
 [testenv]
 # Use the system packages for pyopencl, numpy, scipy etc
@@ -45,6 +45,16 @@ deps =
 commands =
     reuse lint
 
+[testenv:twine]
+basepython = python3
+skip_install = true
+skipsdist = false
+sitepackages = false
+deps =
+    twine
+commands =
+    twine check {distdir}/*
+
 
 # Additional configuration for non-tox tools
 [flake8]