activate environment for pyinstaller

.github/workflows/release_linux.yml

@@ -26,8 +26,8 @@ jobs:
         pip install PyInstaller==4.10
     - name: Build binary
       run: |
+        . build/bin/activate
         pyinstaller --onefile -n nanovna-saver nanovna-saver.py
-
     - name: Archive production artifacts
       uses: actions/upload-artifact@v1
       with: