chore: ignore TypeScript major bumps until astro check supports TS 7

typescript must stay on 6.x for @astrojs/check, so tell Dependabot to stop
re-proposing the TS 5->7 major update. The TS 7 path is tracked separately via
@typescript/native-preview. Remove this ignore once @astrojs/check supports TS 7.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 64357866-3a3f-4fd8-914b-77826de5be5a

Author: GeekTrainer

.github/dependabot.yml

@@ -17,3 +17,12 @@ updates:
         dependency-type: production
         update-types:
           - patch
+    ignore:
+      # `typescript` is pinned to the 6.x line because our only type-checker,
+      # @astrojs/check, peers on `typescript@^5 || ^6` and does not yet support
+      # TypeScript 7. The TS 7 toolchain is tracked separately via the
+      # `@typescript/native-preview` (tsgo) dev dependency and the `check:tsgo`
+      # script. Drop this ignore once @astrojs/check supports TypeScript 7.
+      - dependency-name: typescript
+        update-types:
+          - version-update:semver-major