Fix pip install on windows (myhdl#422)

* Test

* Move from python -m pip to just pip

.github/workflows/test_checkin.yml

@@ -133,9 +133,9 @@ jobs:
           echo "C:\ProgramData\Chocolatey\bin" >> $GITHUB_PATH
       - name: Install dependencies
         run: |
-          python -m pip install --upgrade pip
-          python -m pip install --upgrade -r requirements.txt
-          python -m pip install .
+          pip install --upgrade pip
+          pip install --upgrade -r requirements.txt
+          pip install .
       - name: Run Tests
         run: |
           make ${{ env.CI_TARGET }}

pytest.ini

@@ -1,4 +1,4 @@
 [pytest]
 filterwarnings = 
     error::DeprecationWarning
-    error::pytest.PytestWarning
+    error::pytest.PytestWarning