package.json: use semver for webpack dependency

As far as I can tell dspace-angular doesn't explicitly need any
particular version of webpack itself, but angular-cli specifies
a semver string of `^5.54.0` so we should do the same.

Also, our dependabot configuration currently considers minor and
patch versions for updates, so we should not be using an exact
version here anyway.

See: https://github.com/angular/angular-cli/blob/18.2.x/packages/ngtools/webpack/package.json

Author: alanorth

package-lock.json

@@ -237,7 +237,7 @@
     "sass-resources-loader": "^2.2.5",
     "ts-node": "^8.10.2",
     "typescript": "~5.4.5",
-    "webpack": "5.101.0",
+    "webpack": "^5.54.0",
     "webpack-cli": "^5.1.4",
     "webpack-dev-server": "^5.2.2"
   }