fix: code scanning alert no. 12: Reflected cross-site scripting (#5078)

Signed-off-by: Simon Heather <32168619+X-Guardian@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

server/controllers/events/events_controller.go

@@ -16,6 +16,7 @@ package events
 import (
 	"encoding/json"
 	"fmt"
+	"html"
 	"io"
 	"net/http"
 	"strings"
@@ -178,7 +179,7 @@ func (e *VCSEventsController) handleGithubPost(w http.ResponseWriter, r *http.Re
 		return
 	}
 
-	githubReqID := "X-Github-Delivery=" + r.Header.Get("X-Github-Delivery")
+	githubReqID := "X-Github-Delivery=" + html.EscapeString(r.Header.Get("X-Github-Delivery"))
 	logger := e.Logger.With("gh-request-id", githubReqID)
 	scope := e.Scope.SubScope("github_event")