Replace cdn.dl.k8s.io with dl.k8s.io (#227) (#228)

The cdn.dl.k8s.io domain is no longer available. Switch all download URLs back to dl.k8s.io.

src/helpers.ts

@@ -14,14 +14,14 @@ export function getKubectlArch(): string {
 export function getkubectlDownloadURL(version: string, arch: string): string {
    switch (os.type()) {
       case 'Linux':
-         return `https://cdn.dl.k8s.io/release/${version}/bin/linux/${arch}/kubectl`
+         return `https://dl.k8s.io/release/${version}/bin/linux/${arch}/kubectl`
 
       case 'Darwin':
-         return `https://cdn.dl.k8s.io/release/${version}/bin/darwin/${arch}/kubectl`
+         return `https://dl.k8s.io/release/${version}/bin/darwin/${arch}/kubectl`
 
       case 'Windows_NT':
       default:
-         return `https://cdn.dl.k8s.io/release/${version}/bin/windows/${arch}/kubectl.exe`
+         return `https://dl.k8s.io/release/${version}/bin/windows/${arch}/kubectl.exe`
    }
 }
 
@@ -30,7 +30,7 @@ export async function getLatestPatchVersion(
    minor: string
 ): Promise<string> {
    const version = `${major}.${minor}`
-   const sourceURL = `https://cdn.dl.k8s.io/release/stable-${version}.txt`
+   const sourceURL = `https://dl.k8s.io/release/stable-${version}.txt`
    try {
       const downloadPath = await toolCache.downloadTool(sourceURL)
       const latestPatch = fs