Bump gatsby-plugin-sitemap from 6.14.0 to 6.15.0 in /website (#314)

Bumps [gatsby-plugin-sitemap](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-sitemap) from 6.14.0 to 6.15.0.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-sitemap/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-sitemap@6.15.0/packages/gatsby-plugin-sitemap)

---
updated-dependencies:
- dependency-name: gatsby-plugin-sitemap
  dependency-version: 6.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

website/package.json

@@ -28,7 +28,7 @@
     "gatsby-plugin-react-helmet": "^6.14.0",
     "gatsby-plugin-sass": "^6.15.0",
     "gatsby-plugin-sharp": "^5.14.0",
-    "gatsby-plugin-sitemap": "^6.14.0",
+    "gatsby-plugin-sitemap": "^6.15.0",
     "gatsby-source-filesystem": "^5.14.0",
     "gatsby-transformer-remark": "^6.14.0",
     "gatsby-transformer-sharp": "^5.14.0",

website/yarn.lock

@@ -5721,10 +5721,10 @@ gatsby-plugin-sharp@^5.14.0:
     semver "^7.5.3"
     sharp "^0.32.6"
 
-gatsby-plugin-sitemap@^6.14.0:
-  version "6.14.0"
-  resolved "https://registry.yarnpkg.com/gatsby-plugin-sitemap/-/gatsby-plugin-sitemap-6.14.0.tgz#e7815fc454499409350b2d8af9a0910208da4884"
-  integrity sha512-pF7sv+4IdihiyMaQcXzxXrsA8XzbCwJuiDmHN8PvxrMa2v9FFwjhGXEX/dwJAOSDz98tauT7PRj8Ys4F2DfOTQ==
+gatsby-plugin-sitemap@^6.15.0:
+  version "6.15.0"
+  resolved "https://registry.yarnpkg.com/gatsby-plugin-sitemap/-/gatsby-plugin-sitemap-6.15.0.tgz#4b44d6c3b88c1b1149812bb0542832584149c860"
+  integrity sha512-T4gchKmWh9n3ld0AylXfyfr498IAwMawIHM9U4oC8twxpOb6AOtmitba3UvSykUK1/FBNEriJFVi+slQylUZvg==
   dependencies:
     "@babel/runtime" "^7.20.13"
     common-tags "^1.8.2"