add spack post-installation testing

This Merge Request:

• adds or fixes tests for most EBRAINS (top-level) Spack packages
• adapts gitlab CI and installation script to run tests at installation time

packages/py-tvb-library/package.py

@@ -58,6 +58,5 @@ class PyTvbLibrary(PythonPackage):
     @run_after('install')
     @on_package_attributes(run_tests=True)
     def install_test(self):
-
-        pytest = which('pytest')
-        pytest('tvb.tests.library')
+        with working_dir('spack-test', create=True):
+            python('-m', 'pytest --pyargs tvb.tests.library')