Explicitly install support for target of release builds.

Author: mkantor

.github/workflows/release.yml

@@ -67,6 +67,7 @@ jobs:
           ~/.cargo/git
           target/release
         key: release-${{ runner.os }}-${{ github.job }}-${{ secrets.CI_CACHE_VERSION }}
+    - run: rustup target add ${{ matrix.target }}
     - run: cargo build --release --target ${{ matrix.target }}
     - name: package binary
       shell: bash