Update future_testing.yml

Author: jhavl

.github/workflows/future_testing.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         os: [windows-latest, ubuntu-latest, macos-latest]
-        python-version: [3.7, 3.8, 3.9, 3.10]
+        python-version: [3.7, 3.8, 3.9, '3.10']
 
     steps:
     - name: Set up Python ${{ matrix.python-version }}