Replace package aws-sdk/signature-v4 with smithy

This package is not modified since 2 years now, and the
replacement is also mentioned in the documentation: https://www.npmjs.com/package/@aws-sdk/signature-v4?activeTab=readme

This PR is simply replacing the packages in the code, this is
a drop-in replacement and there's no need to apply any other changes.

This has been already done in one of the open-source plugins we own,
as well as in our Backstage instance, and all worked just like before.

Signed-off-by: ivangonzalezacuna <ivangonzalezacuna@gmail.com>

plugins/kubernetes-backend/package.json

@@ -45,7 +45,6 @@
   "dependencies": {
     "@aws-crypto/sha256-js": "^5.0.0",
     "@aws-sdk/credential-providers": "^3.350.0",
-    "@aws-sdk/signature-v4": "^3.347.0",
     "@azure/identity": "^4.0.0",
     "@backstage/backend-plugin-api": "workspace:^",
     "@backstage/catalog-client": "workspace:^",
@@ -62,6 +61,7 @@
     "@google-cloud/container": "^5.0.0",
     "@jest-mock/express": "^2.0.1",
     "@kubernetes/client-node": "1.4.0",
+    "@smithy/signature-v4": "^4.1.0",
     "@types/http-proxy-middleware": "^1.0.0",
     "express": "^4.17.1",
     "express-promise-router": "^4.1.0",