Add toolchain setup to all features test

When splitting the workflows in c26ac6b, the all features test workflow
was left without a step to setup the Rust toolchain. This has led to
failures as the wrong toolchain can get used in some situations.

.github/workflows/test.yml

@@ -89,6 +89,11 @@ jobs:
       - name: Checkout the repo
         uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
 
+      - name: Install Rust toolchain
+        run: |
+          rustup toolchain install --no-self-update stable --profile minimal
+          rustup default stable
+
       - name: All Features
         env:
           PHYLUM_API_KEY: ${{ secrets.PHYLUM_TOKEN_STAGING }}