Replace unmaintained actions-rs/* actions in CI workflows (#29)

Basically all of the `actions-rs/*` actions are unmaintained. See
<actions-rs/toolchain#216> for more
information. Due to their age they generate several warnings in
CI runs.

To get rid of those warnings the occurrences of
`actions-rs/toolchain` are replaced by `dtolnay/rust-toolchain`,
and the occurrences of `actions-rs/cargo` are replaced by direct
invocations of `cargo`.

Author: striezel

.github/workflows/main.yml

@@ -28,17 +28,10 @@ jobs:
     name: Check
     runs-on: ubuntu-latest
     steps:
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
+      - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2
       - run: sudo apt-get update
       - run: sudo apt-get install libsoup2.4 javascriptcoregtk-4.0
       - run: sudo apt install libwebkit2gtk-4.0-dev libgtk-3-dev libayatana-appindicator3-dev
       - uses: actions/checkout@v3
-      - uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --all --examples --tests --exclude dioxus-ios-demo
+      - run: cargo check --all --examples --tests --exclude dioxus-ios-demo