Updates reference of tf version for CI tests to run against.

Author: arcra

.github/workflows/ci.yml

@@ -30,7 +30,10 @@ env:
   BUILDTOOLS_VERSION: '3.0.0'
   BUILDIFIER_SHA256SUM: 'e92a6793c7134c5431c58fbc34700664f101e5c9b1c1fcd93b97978e8b7f88db'
   BUILDOZER_SHA256SUM: '3d58a0b6972e4535718cdd6c12778170ea7382de7c75bc3728f5719437ffb84d'
-  TENSORFLOW_VERSION: 'tf-nightly==2.16.0.dev20240206'
+  # By the time we created TB patch release 2.15.2 TF 2.15.0 had already been
+  # released, and there were no more nightly versions available.
+  # This is the latest release available for TF 2.15.x.
+  TENSORFLOW_VERSION: 'tensorflow==2.15.0.post1'
 
 jobs:
   build: