ci: add step to validate release manifests

As requested in
argoproj#14044 (comment),
this adds a simple step to each E2E suite that validates the release
manifests using server-side field validation. This is intended to catch
simple issues, e.g. typos in a field:
```
$ make manifests-validate
<SNIP>
deployment.apps/postgres serverside-applied (server dry run)
The CustomResourceDefinition "clusterworkflowtemplates.argoproj.io" is invalid:
* spec.validation.openAPIV3Schema.properties[apiVersion].type: Invalid value: "TYPO": must be string
* spec.validation.openAPIV3Schema.properties[apiVersion].type: Unsupported value: "TYPO": supported values: "array", "boolean", "integer", "number", "object", "string"
make: *** [Makefile:452: manifests-validate] Error 1
```

Signed-off-by: Mason Malone <[email protected]>

.github/workflows/ci-build.yaml

@@ -322,6 +322,8 @@ jobs:
           echo "  user:" >> $KUBECONFIG
           echo "    token: xxxxxx" >> $KUBECONFIG
           until kubectl cluster-info ; do sleep 10s ; done
+      - name: Validate release manifests
+        run: make manifests-validate
       - name: Download images
         uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:

Makefile

@@ -447,6 +447,10 @@ dist/manifests/%: manifests/%
 
 # lint/test/etc
 
+.PHONE: manifests-validate
+manifests-validate:
+	kubectl apply --server-side --validate=strict --dry-run=server -f 'manifests/*.yaml'
+
 $(GOPATH)/bin/golangci-lint: Makefile
 	curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b `go env GOPATH`/bin v1.61.0