Fix broken links to changelog from release note pages (#12661)

The problem that is described in the linked issue seems to occur due to the
Templating system not working for the snippet `{{site.repo.flutter}}`.
What differentiates the release notes pages from others is the option
`skipTemplateRendering` in the front matter, which is set to `true`.
Fix this by replacing the usage of template variables with the underlying values.

Fixes #12660

Author: iakdis

src/content/release/release-notes/release-notes-3.0.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.0.0.
 For information about subsequent bug-fix releases,
 see our [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## If you see warnings about bindings
 

src/content/release/release-notes/release-notes-3.10.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.10.0.
 For information about subsequent bug-fix releases,
 see our [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Framework
 

src/content/release/release-notes/release-notes-3.13.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.13.0.
 For information about subsequent bug-fix releases,
 see our [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Framework
 

src/content/release/release-notes/release-notes-3.16.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.16.0.
 For information about subsequent bug-fix releases,
 see our [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Flutter
 

src/content/release/release-notes/release-notes-3.19.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.19.0.
 For information about subsequent bug-fix releases,
 see our [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Flutter
 

src/content/release/release-notes/release-notes-3.22.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.22.0.
 For information about subsequent bug-fix releases,
 see our [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Flutter
 

src/content/release/release-notes/release-notes-3.24.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.24.0.
 For information about subsequent bug-fix releases,
 check out the Flutter [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Flutter framework
 

src/content/release/release-notes/release-notes-3.27.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.27.0.
 For information about subsequent bug-fix releases,
 check out the Flutter [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Flutter framework
 

src/content/release/release-notes/release-notes-3.29.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.29.0.
 For information about subsequent bug-fix releases,
 check out the Flutter [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## Flutter framework
 

src/content/release/release-notes/release-notes-3.3.0.md

@@ -9,7 +9,7 @@ This page has release notes for 3.3.0.
 For information about subsequent bug-fix releases,
 see our [CHANGELOG][].
 
-[CHANGELOG]: {{site.repo.flutter}}/blob/main/CHANGELOG.md
+[CHANGELOG]: https://github.com/flutter/flutter/blob/main/CHANGELOG.md
 
 ## What's changed