[GitHub Actions] create virutal env directly

.github/workflows/testing_external_plugins.yaml

@@ -45,13 +45,9 @@ jobs:
         path: .venv
         key: ${{ runner.os }}-${{ hashFiles('poetry.lock') }}-${{ matrix.python-version }}-v2-namespace-plugins
 
-    - name: Install dependencies (1 of 2)
+    - name: Create Virtual Environment
       run: |
-        python -m pip install pip --upgrade
-        pip install poetry
-        poetry config --local virtualenvs.in-project true
-        poetry install --remove-untracked
-        poetry install
+        python -m venv .venv
 
     - name: Activate Virtual Environment (Linux)
       if: startsWith(matrix.os, 'ubuntu')
@@ -65,9 +61,11 @@ jobs:
       if: startsWith(matrix.os, 'windows')
       run: venv/Scripts/activate
 
-    - name: Install dependencies (2 of 2)
+    - name: Install dependencies
       run: |
+        python -m pip install .
         python -m pip install ./tests/external_plugins_src/
+        python -m pip install pytest behave
         cd features
     # installed test plugins aren't recognized by "behave" if run from the
     # project's root folder