Use common CI patterns (#9)

* .github: Use cross-install action

* .github: Use set-msrv workflow

.github/actions/cross-tests/action.yml

@@ -20,14 +20,7 @@ runs:
           toolchain: ${{ inputs.rust }}
           target: ${{ inputs.target }}
           override: true
-      - name: Install precompiled cross
-        run: |
-          export URL=$(curl -s https://api.github.com/repos/cross-rs/cross/releases/latest | \
-            jq -r '.assets[] | select(.name | contains("x86_64-unknown-linux-gnu.tar.gz")) | .browser_download_url')
-          wget -O /tmp/binaries.tar.gz $URL
-          tar -C /tmp -xzf /tmp/binaries.tar.gz
-          mv /tmp/cross ~/.cargo/bin
-        shell: bash
+      - uses: RustCrypto/actions/cross-install@master
       - if: ${{ inputs.features != 'NO_FEATURE' }}
         run: |
           cd ${{ inputs.package }}

.github/workflows/keccak.yml

@@ -14,19 +14,14 @@ defaults:
     working-directory: keccak
 
 env:
-  MSRV: 1.41.0
   RUSTFLAGS: "-Dwarnings"
   CARGO_INCREMENTAL: 0
 
 jobs:
   set-msrv:
-    runs-on: ubuntu-latest
-    outputs:
-      msrv: ${{ steps.msrv.outputs.msrv }}
-    steps:
-      - uses: actions/checkout@v2
-      - id: msrv
-        run: echo "::set-output name=msrv::$(echo $MSRV)"
+    uses: RustCrypto/actions/.github/workflows/set-msrv.yml@master
+    with:
+        msrv: 1.41.0
 
   build:
     needs: set-msrv