backend-*-api: remove unused express dependencies

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

packages/backend-plugin-api/src/services/definitions/HttpAuthService.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { Request, Response } from 'express';
+import type { Request, Response } from 'express';
 import { BackstageCredentials, BackstagePrincipalTypes } from './AuthService';
 
 /**

packages/backend-plugin-api/src/services/definitions/HttpRouterService.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { Handler } from 'express';
+import type { Handler } from 'express';
 
 /**
  * Options for {@link HttpRouterService.addAuthPolicy}.

packages/backend-plugin-api/src/services/definitions/RootHttpRouterService.ts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { Handler } from 'express';
+import type { Handler } from 'express';
 
 /**
  * HTTP route registration for root services.