Fix dependency on tockloader 1.4

Now that it has been released and pushed to pypi, make sure that
tockloader is at least 1.4 version

.github/workflows/python.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip setuptools wheel
-          pip install tockloader pylint
+          pip install 'tockloader~=1.4' pylint
       - name: Register matcher
         run: echo ::add-matcher::./.github/python_matcher.json
       - name: Test code with pylint