Install Rust toolchain later

`brew` seems to be breaking the rustup installed by rust-toolchain:

```
==> Migrating formula rustup-init to rustup
==> Unlinking rustup-init
==> Moving rustup-init versions to /opt/homebrew/Cellar/rustup
==> Relinking rustup
```

Let's see if this fixes it.

.github/workflows/ci.yml

@@ -191,14 +191,6 @@ jobs:
         with:
           submodules: recursive
 
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: nightly
-          components: rust-src
-          targets: aarch64-unknown-linux-musl,x86_64-unknown-linux-musl
-
-      - uses: Swatinem/rust-cache@v2
-
       - name: Install prerequisites
         if: runner.os == 'Linux'
         # ubuntu-22.04 comes with clang 14[0] which doesn't include support for signed and 64bit
@@ -243,6 +235,14 @@ jobs:
           echo $(brew --prefix)/opt/gnu-tar/libexec/gnubin >> $GITHUB_PATH
           echo $(brew --prefix)/opt/llvm/bin >> $GITHUB_PATH
 
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly
+          components: rust-src
+          targets: aarch64-unknown-linux-musl,x86_64-unknown-linux-musl
+
+      - uses: Swatinem/rust-cache@v2
+
       - name: bpf-linker
         if: runner.os == 'macOS'
         # NB: rustc doesn't ship libLLVM.so on macOS, so disable proxying (default feature). We also