Bump CI oldest nightly

Author: Meziu

.github/workflows/ci.yml

@@ -43,7 +43,7 @@ jobs:
       matrix:
         toolchain:
           # Oldest supported nightly
-          - nightly-2024-03-10
+          - nightly-2024-08-31
           - nightly
 
     continue-on-error: ${{ matrix.toolchain == 'nightly' }}