experiment: don't duplicate the MSRV

Author: danieleades

.github/workflows/test.yml

@@ -51,9 +51,13 @@ jobs:
         features: ["", --features serde, --features tokio-1]
     steps:
       - uses: actions/checkout@master
+      - name: Get MSRV from Cargo.toml
+        run: |
+          MSRV=$(grep 'rust-version' Cargo.toml | sed 's/.*= *"\(.*\)".*/\1/')
+          echo "MSRV=$MSRV" >> $GITHUB_ENV
       - uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: 1.70.0
+          toolchain: ${{ env.MSRV }}
       - uses: taiki-e/install-action@cargo-no-dev-deps
       - run: cargo no-dev-deps check --all --all-targets ${{ matrix.features }}