Explicitly disable v7 future flags to suppress warnings

Rather than removing the future prop, set v7_relativeSplatPath and
v7_startTransition to false so react-router stops logging deprecation
warnings.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/ten-mammals-invite.md

@@ -53,4 +53,4 @@
 '@backstage/plugin-org': patch
 ---
 
-Updated `react-router-dom` peer dependency to `^6.30.2`.
+Updated `react-router-dom` peer dependency to `^6.30.2` and explicitly disabled v7 future flags to suppress deprecation warnings.

packages/frontend-test-utils/src/app/renderInTestApp.tsx

@@ -208,7 +208,13 @@ export function renderInTestApp<const TApiPairs extends any[] = any[]>(
         RouterBlueprint.make({
           params: {
             component: ({ children }) => (
-              <MemoryRouter initialEntries={options?.initialRouteEntries}>
+              <MemoryRouter
+                initialEntries={options?.initialRouteEntries}
+                future={{
+                  v7_relativeSplatPath: false,
+                  v7_startTransition: false,
+                }}
+              >
                 {children}
               </MemoryRouter>
             ),

packages/frontend-test-utils/src/app/renderTestApp.tsx

@@ -150,7 +150,13 @@ export function renderTestApp<const TApiPairs extends any[] = any[]>(
         RouterBlueprint.make({
           params: {
             component: ({ children }) => (
-              <MemoryRouter initialEntries={options?.initialRouteEntries}>
+              <MemoryRouter
+                initialEntries={options?.initialRouteEntries}
+                future={{
+                  v7_relativeSplatPath: false,
+                  v7_startTransition: false,
+                }}
+              >
                 {children}
               </MemoryRouter>
             ),

plugins/app/src/extensions/AppRoot.tsx

@@ -198,7 +198,17 @@ export interface AppRouterProps {
 function DefaultRouter(props: PropsWithChildren<{}>) {
   const configApi = useApi(configApiRef);
   const basePath = getBasePath(configApi);
-  return <BrowserRouter basename={basePath}>{props.children}</BrowserRouter>;
+  return (
+    <BrowserRouter
+      basename={basePath}
+      future={{
+        v7_relativeSplatPath: false,
+        v7_startTransition: false,
+      }}
+    >
+      {props.children}
+    </BrowserRouter>
+  );
 }
 
 /**