update python version in translations workflow (#1445)

.github/workflows/translations.yml

@@ -16,7 +16,7 @@ jobs:
           git submodule update --init --recursive
       - uses: actions/setup-python@v1
         with:
-          python-version: '3.x'
+          python-version: '3.9.x'
       - env:
           CROWDIN_API_KEY: ${{ secrets.CROWDIN_API_KEY }}
         run: |