ci: workaround for get.helm.sh outage (#20552)

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Author: johnstcn

.github/workflows/ci.yaml

@@ -204,9 +204,17 @@ jobs:
 
       # Needed for helm chart linting
       - name: Install helm
-        uses: azure/setup-helm@1a275c3b69536ee54be43f2070a358922e12c8d4 # v4.3.1
-        with:
-          version: v3.9.2
+        # uses: azure/setup-helm@1a275c3b69536ee54be43f2070a358922e12c8d4 # v4.3.1
+        # with:
+          # version: v3.9.2
+        # The below is taken from https://helm.sh/docs/intro/install/#from-apt-debianubuntu
+        run: |
+          set -euo pipefail
+          sudo apt-get install curl gpg apt-transport-https --yes
+          curl -fsSL https://packages.buildkite.com/helm-linux/helm-debian/gpgkey | gpg --dearmor | sudo tee /usr/share/keyrings/helm.gpg > /dev/null
+          echo "deb [signed-by=/usr/share/keyrings/helm.gpg] https://packages.buildkite.com/helm-linux/helm-debian/any/ any main" | sudo tee /etc/apt/sources.list.d/helm-stable-debian.list
+          sudo apt-get update
+          sudo apt-get install helm
 
       - name: make lint
         run: |