fix: packages/backend-common/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-HTTPPROXYMIDDLEWARE-9691387
- https://snyk.io/vuln/SNYK-JS-HTTPPROXYMIDDLEWARE-9691389

Author: snyk-bot

packages/backend-common/package.json

@@ -50,15 +50,15 @@
     "@aws-sdk/client-s3": "^3.350.0",
     "@aws-sdk/credential-providers": "^3.350.0",
     "@aws-sdk/types": "^3.347.0",
-    "@backstage/backend-app-api": "workspace:^",
+    "@backstage/backend-app-api": "0.7.6",
     "@backstage/backend-dev-utils": "workspace:^",
-    "@backstage/backend-plugin-api": "workspace:^",
+    "@backstage/backend-plugin-api": "0.6.19",
     "@backstage/cli-common": "workspace:^",
     "@backstage/config": "workspace:^",
     "@backstage/config-loader": "workspace:^",
     "@backstage/errors": "workspace:^",
     "@backstage/integration": "workspace:^",
-    "@backstage/integration-aws-node": "workspace:^",
+    "@backstage/integration-aws-node": "0.1.0",
     "@backstage/types": "workspace:^",
     "@google-cloud/storage": "^6.0.0",
     "@keyv/memcache": "^1.3.5",