chore(Svg.Skia): Pin Svg.Skia to 3.0.3 in templates/sdk to avoid breaking changes introduced with version ≥ 3.0.4 (backport #1753)

[mergify]

GitHub Issue: fixes unoplatform/uno#21372
Tracking issue for missing API support: unoplatform/uno#21378

PR Type

• Bugfix

What is the current behavior?

Svg.Skia was updated automatically to versions ≥ 3.0.4, which introduces new ISvgAssetLoader APIs (GetFontMetrics, MeasureText, GetTextPath).
Uno’s current SkiaAssetLoader does not implement these methods yet, leading to a TypeLoadException and broken SVG rendering.

What is the new behavior?

Pin Svg.Skia to 3.0.3 in templates/sdk to avoid the regression.
This unblocks apps until Uno’s SkiaAssetLoader is updated to support the new APIs.

PR Checklist

• Linked to an issue (GitHub or internal)
• Includes context for why the version is pinned

Other information

• Svg.Skia is also excluded from automatic dependency updates by the updater tool (see feat(Uno.Sdk.Updater): Add CLI exclude-file support and improve manifest merge logic #1752).

---

This is an automatic backport of pull request #1753 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 3f42acb has failed:

On branch mergify/bp/release/stable/6.2/pr-1753
Your branch is up to date with 'origin/release/stable/6.2'.

You are currently cherry-picking commit 3f42acb.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/Uno.Sdk/ReadMe.md
	both modified:   src/Uno.Sdk/packages.json

no changes added to commit (use "git add" and/or "git commit -a")

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