[Snyk] Security upgrade astro from 5.7.13 to 5.15.6 (#4865)

* fix: packages/site/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-ASTRO-13961342
- https://snyk.io/vuln/SNYK-JS-ASTRO-13961435

* chore(deps): update lock file

* chore(deps): update lock file

---------

Co-authored-by: snyk-bot <[email protected]>
Co-authored-by: Austin Sullivan <[email protected]>

Author: 3 people

packages/site/package.json

@@ -14,7 +14,7 @@
   },
   "dependencies": {
     "@patternfly/patternfly-doc-core": "^1.13.1",
-    "astro": "^5.7.13"
+    "astro": "^5.15.6"
   },
   "devDependencies": {
     "tsx": "^4.19.0"