Build(deps-dev): Bump @swc/core from 1.7.18 to 1.7.21 (#28618)

Bumps [@swc/core](https://github.com/swc-project/swc) from 1.7.18 to 1.7.21.
- [Release notes](https://github.com/swc-project/swc/releases)
- [Changelog](https://github.com/swc-project/swc/blob/main/CHANGELOG.md)
- [Commits](https://github.com/swc-project/swc/compare/v1.7.18...v1.7.21)

---
updated-dependencies:
- dependency-name: "@swc/core"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

app/assets/javascripts/discourse/package.json

@@ -57,7 +57,7 @@
     "@glimmer/component": "^1.1.2",
     "@glimmer/tracking": "^1.1.2",
     "@popperjs/core": "^2.11.8",
-    "@swc/core": "^1.7.18",
+    "@swc/core": "^1.7.21",
     "@types/jquery": "^3.5.30",
     "@types/qunit": "^2.19.10",
     "@types/rsvp": "^4.0.9",