Upgrade to go 1.21 in ci

Author: ackleymi

.github/workflows/ci.yaml

@@ -26,7 +26,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v2
         with:
-          go-version: '1.18'
+          go-version: '1.21'
       - name: Install golangci-lint
         run: |
           curl -sSLO https://github.com/golangci/golangci-lint/releases/download/v$GOLANGCI_LINT_VERSION/golangci-lint-$GOLANGCI_LINT_VERSION-linux-amd64.tar.gz
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [1.18]
+        go: [1.21]
         fix-version:
           -
           - fix40