Update rust.yml

Author: ge3224

.github/workflows/rust.yml

@@ -13,9 +13,16 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        toolchain:
+          - stable
+          - beta
+          - nightly
 
     steps:
     - uses: actions/checkout@v3
+    - run: rustup update ${{ matrix.toolchain }} && rustup default ${{ matrix.toolchain }}
     - name: Build
       run: cargo build --verbose
     - name: Run tests