CI: Go back to manual rustup+cargo install

The actions-rs helpers spew out a bunch of warnings about using deprecated features that are going away soon. They also aren't any faster than the old manual way of doing things which worked fine.

.github/workflows/fuzz.yml

@@ -16,18 +16,14 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
-    - uses: actions-rs/toolchain@v1
-      name: Install Rust
-      with:
-          profile: minimal
-          toolchain: nightly
-          override: true
-    - uses: actions-rs/install@v0.1
-      name: Install cargo-fuzz
-      with:
-          crate: cargo-fuzz
-          version: latest
-          use-tool-cache: true
+    - name: Install nightly Rust
+      shell: bash
+      run: |
+        curl -sSL https://sh.rustup.rs | sh -s -- -y --profile=minimal --default-toolchain=nightly
+        export PATH="$HOME/.cargo/bin:$PATH"
+        echo "$HOME/.cargo/bin" >> $GITHUB_PATH
+    - name: Install cargo fuzz
+      run: cargo install cargo-fuzz
     - name: Build
       run: cargo build --verbose
     - name: Cache fuzzy corpus