Use toolchain file as single source of truth

Author: mlafeldt

.github/workflows/release.yaml

@@ -12,10 +12,6 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: actions-rust-lang/setup-rust-toolchain@v1
-        with:
-          toolchain: stable
-          target: ${{ matrix.target }}
-          components: 'rustfmt, clippy'
 
       # cargo publish
       - name: publish crates

.github/workflows/rust.yaml

@@ -28,9 +28,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
-          toolchain: stable
           target: ${{ matrix.target }}
-          components: 'rustfmt, clippy'
 
       # download libduckdb
       - uses: robinraju/[email protected]
@@ -111,7 +109,6 @@ jobs:
             index-${{ runner.os }}-
       - uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
-          toolchain: stable
           target: x86_64-pc-windows-msvc
 
       - run: cargo install cargo-examples