Upgrade toolchain to 2024-09-01

We might actually want a more recent toolchain to support
rust3ds/ctru-rs#214 but I'm just testing things
for now

Author: ian-h-chamberlain

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         toolchain:
           # Oldest supported nightly
-          - nightly-2024-02-18
+          - nightly-2024-09-01
           - nightly
         ctru-rs-ref:
           # "known good" version of `test-runner` crate