fix certificate issues in KubernetesProxy

Signed-off-by: Riley Martine <rmartine@integralads.com>

.changeset/good-rabbits-exist.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-kubernetes-backend': patch
+---
+
+Fixed bug in KubernetesProxy where Host header was not propagated, leading to certificate issues

plugins/kubernetes-backend/src/service/KubernetesProxy.ts

@@ -137,6 +137,7 @@ export class KubernetesProxy {
       middleware = createProxyMiddleware({
         logProvider: () => logger,
         secure: !originalCluster.skipTLSVerify,
+        changeOrigin: true,
         router: async req => {
           // Re-evaluate the cluster on each request, in case it has changed
           const cluster = await this.getClusterForRequest(req);