update tests to use TF < 2.12

.github/workflows/tests.yml

@@ -27,7 +27,7 @@ jobs:
           pip install flake8 pytest pytest-cov
           pip --default-timeout=100 install -e .
           pip --default-timeout=100 install "keras<3.0.0"
-          pip --default-timeout=100 install "tensorflow>=2.0.0"
+          pip --default-timeout=100 install "tensorflow>=2.0.0,<2.12"
       - name: Lint with flake8
         run: |
           # stop the build if there are Python syntax errors or undefined names