Create new Flannel version

addons/flannel/0.26.1/Manifest

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+image flannel-flannel docker.io/flannel/flannel:v0.26.1
+image flannel-flannel-cni-plugin docker.io/flannel/flannel-cni-plugin:v1.5.1-flannel2

addons/flannel/0.26.1/flannel-ethtool.service

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+[Unit]
+Description=Disable vxlan checksum offloading for flannel.1
+After=sys-devices-virtual-net-flannel.1.device
+Requires=sys-devices-virtual-net-flannel.1.device
+
+[Service]
+Type=oneshot
+ExecStart=/sbin/ethtool -K flannel.1 tx-checksum-ip-generic off
+RemainAfterExit=yes
+
+[Install]
+WantedBy=sys-devices-virtual-net-flannel.1.device

addons/flannel/0.26.1/host-preflight.yaml

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+apiVersion: troubleshoot.sh/v1beta2
+kind: HostPreflight
+metadata:
+  name: flannel
+spec:
+  collectors:
+    - udpPortStatus:
+        collectorName: Flannel UDP port 8472
+        port: 8472
+        exclude: '{{kurl .IsUpgrade }}'
+  analyzers:
+    - udpPortStatus:
+        checkName: "Flannel UDP port 8472 status"
+        collectorName: Flannel UDP port 8472
+        exclude: '{{kurl .IsUpgrade }}'
+        outcomes:
+          - warn:
+              when: "address-in-use"
+              message: Another process is already listening on port
+          - fail:
+              when: "error"
+              message: Unexpected port status
+          - pass:
+              when: "connected"
+              message: Port is open
+          - warn:
+              message: Unexpected port status