release workflow: remove Go setup action

Release builds are performed from within a Dockerfile-defined
environment and do not require Go to be installed in the GitHub Actions
runner environment.

Signed-off-by: Samuel Karp <samuelkarp@google.com>

.github/workflows/release.yml

@@ -66,10 +66,6 @@ jobs:
           - linux/riscv64
           - windows/amd64
     steps:
-      - name: Install Go
-        uses: actions/setup-go@v2
-        with:
-          go-version: ${{ env.GO_VERSION }}
       - name: Set env
         shell: bash
         env: