ci: fix

.github/workflows/rust.yml

@@ -23,6 +23,9 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: ${{ matrix.rust }}
+          # A build.rs of a transitive dependency requires this (at least on the
+          # Windows builds), WTF!
+          components: rustfmt
       - uses: Swatinem/rust-cache@v2
         with:
           key: "${{ matrix.runs-on }}-${{ matrix.rust }}"