tests: upgrade rust compiler for E2E tests

Author: zyzniewski-reef

.github/workflows/e2e-subtensor-tests.yaml

@@ -52,7 +52,7 @@ jobs:
       max-parallel: 8  # Set the maximum number of parallel jobs
       matrix:
         rust-branch:
-          - nightly-2024-03-05
+          - stable
         rust-target:
           - x86_64-unknown-linux-gnu
         os: