Update github workflow

pgtest was missing for running aiida related tests

Author: bastonero

.github/workflows/python-testsuite.yml

@@ -35,7 +35,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install flake8 pytest aiida-core aiida-quantumespresso
+        pip install flake8 pytest~=6.0 pgtest~=1.3 aiida-core~=2.3 aiida-quantumespresso~=4.3
         if [ ${{matrix.python-version}} -eq 2.7 ]; then pip install -r requirements2.txt;
         else pip install -r requirements.txt; fi