Fix source build condition (#188)

Fix conditional for generating source for pypi update

Author: rogebrd

.github/workflows/pypiupload.yml

@@ -28,9 +28,9 @@ jobs:
       run: |
         python setup.py bdist_wheel
     - name: Build Sources
+      if: matrix.python-version == '3.x'
       run: |
         python setup.py sdist
-      if: ${{ matrix.python-version }} == '3.x'
     - name: Publish
       env:
         TWINE_USERNAME: __token__