fix(ci): bump go version for govulncheck in ci.yml

Author: andrewmbenton

.github/workflows/ci.yml

@@ -92,6 +92,6 @@ jobs:
     - uses: actions/checkout@v3
     - uses: actions/setup-go@v4
       with:
-        go-version: '1.20.6'
+        go-version: '1.21.0-rc.4'
     - run: go install golang.org/x/vuln/cmd/govulncheck@latest
     - run: govulncheck ./...