Convert mermaid to svg for CRI blog post

The mermaid still does not render in production, so we convert it to an
SVG for now.

Signed-off-by: Sascha Grunert <[email protected]>

Author: saschagrunert

content/en/blog/_posts/2024-05-01-cri-streaming-explained/flow.mermaid

@@ -0,0 +1,29 @@
+sequenceDiagram
+    participant crictl
+    participant kubectl
+    participant API as API Server
+    participant kubelet
+    participant runtime as Container Runtime
+    participant streaming as Streaming Server
+    alt Client alternatives
+        Note over kubelet,runtime: Container Runtime Interface (CRI)
+        kubectl->>API: exec, attach, port-forward
+        API->>kubelet: exec, attach, port-forward
+        kubelet->>runtime: Exec, Attach, PortForward
+    else
+        Note over crictl,runtime: Container Runtime Interface (CRI)
+        crictl->>runtime: Exec, Attach, PortForward
+    end
+    runtime->>streaming: New Session
+    streaming->>runtime: HTTP endpoint (URL)
+    alt Client alternatives
+        runtime->>kubelet: Response URL
+        kubelet->>API: 
+        API-->>streaming: Connection upgrade (SPDY or WebSocket)
+        streaming-)API: Stream data
+        API-)kubectl: Stream data
+    else
+        runtime->>crictl: Response URL
+        crictl-->>streaming: Connection upgrade (SPDY or WebSocket)
+        streaming-)crictl: Stream data
+    end