ci: Fix complex plugin installation

Author: edgarrmondragon

.github/workflows/test-plugin-command.yml

@@ -78,9 +78,6 @@ jobs:
           > [Starting test job...](https://github.com/${{github.repository}}/actions/runs/${{github.run_id}})
           > ...
 
-    - name: Create requirements.txt
-      run: echo '${{ env.PIP_URL }}' > requirements.txt
-
     - name: Set up Python
       id: setup-python
       uses: actions/setup-python@8d9ed9ac5c53483de85588cdf95a591a75ab9f55 # v5.5.0
@@ -92,13 +89,16 @@ jobs:
       with:
         version: ">=0.4.30"
 
+    - name: Create virtual environment
+      run: |
+        uv venv
+        echo "VIRTUAL_ENV=${{ steps.setup-python.outputs.python-version }}" >> $GITHUB_ENV
+        echo "PATH=${{ steps.setup-python.outputs.python-version }}:${{ github.env.PATH }}" >> $GITHUB_ENV
+
     - name: Install plugin
       id: plugin-install
-      env:
-        MELTANO__PYTHON_VERSION: ${{ steps.setup-python.outputs.python-version }}
       run: |
-        uv venv
-        uv pip install -r requirements.txt 2>&1 | tee install-output.txt
+        echo ${{ env.PIP_URL }} | xargs uv pip install 2> install-output.txt
         echo "failed=${PIPESTATUS[0]}" >> $GITHUB_ENV
 
     - name: Create installation failure log