Pin older version of tensorflow using keras<3.0

.github/workflows/tests.yml

@@ -42,6 +42,7 @@ jobs:
         run: |
           pip install polars==0.16.18
           pip install pypandoc==1.7.2
+          pip install "tensorflow<2.16"
           pip install git+https://github.com/griffithlab/bigmhc.git#egg=bigmhc
           pip install git+https://github.com/griffithlab/deepimmuno.git#egg=deepimmuno
           pip install -e .