Invoke rust dependency caching after setting up rustc

* Add caching for clippy step
* de-duplicate CI actions

Author: molpopgen

.github/workflows/tests.yml

@@ -25,17 +25,13 @@ jobs:
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           submodules: recursive
-      - uses: Swatinem/rust-cache@v1
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: ${{ matrix.rust }}
           override: true
+      - uses: Swatinem/rust-cache@v1
       - run: sudo apt-get update -y
         if: matrix.os == 'ubuntu-latest'
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: ${{ matrix.rust }}
-          override: true
       - name: cargo check
         run: cargo check 
       - name: cargo check examples
@@ -80,6 +76,7 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
+      - uses: Swatinem/rust-cache@v1
       - run: rustup component add clippy
       - name: clippy (all targets)
         run: cargo clippy --all-targets --all-features -- -D warnings