changed rust versions

.gitea/workflows/ci.yml

@@ -11,15 +11,10 @@ jobs:
   build_and_test:
     name: Timo's Workouts - latest
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        toolchain:
-          - stable
-          - beta
-          - nightly
     steps:
       - uses: actions/checkout@v4
-      - run: rustup update ${{ matrix.toolchain }} && rustup default ${{ matrix.toolchain }}
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+      - run: rustup update stable && rustup default stable
       - run: cargo build --verbose
       - run: cargo test --verbose