DEV: Switch to 'unstable' glint dependencies (#31169)

This may help to resolve the "ScriptType" errors we're seeing in the
language server

.github/dependabot.yml

@@ -68,6 +68,8 @@ updates:
       - dependency-name: "moment-timezone"
       - dependency-name: "@discourse/moment-timezone-names-translations"
       - dependency-name: "squoosh"
+      - dependency-name: "@glint/*" # Using unstable version - don't auto-upgrade to stable
+      - dependency-name: "typescript" # Very sensitive to glint/volar version
     groups:
       babel:
         patterns:

.github/workflows/linting.yml

@@ -88,4 +88,4 @@ jobs:
 
       - name: Glint
         if: ${{ !cancelled() }}
-        run: pnpm glint -p jsconfig.json
+        run: pnpm glint -p jsconfig.json --noEmit