ci: use go install for golangci-lint instead of curl

The curl-based install script downloads from raw.githubusercontent.com
which is unreliable in some network environments. go install is more
reliable and uses the Go module proxy.

.gitea/workflows/ci.yml

@@ -33,8 +33,7 @@ jobs:
           fi
 
       - name: Install golangci-lint
-        run: |
-          curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v2.1.0
+        run: go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@latest
 
       - name: Run lint
         run: golangci-lint run ./...