chore: bump @progress/wct-a11y-spec from 2.18.0 to 2.19.0 in /src-a11y (#3217)

Bumps [@progress/wct-a11y-spec](https://github.com/telerik/web-components-ux) from 2.18.0 to 2.19.0.
- [Commits](https://github.com/telerik/web-components-ux/commits)

---
updated-dependencies:
- dependency-name: "@progress/wct-a11y-spec"
  dependency-version: 2.19.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

src-a11y/package-lock.json

@@ -8,7 +8,7 @@
   "author": "",
   "license": "ISC",
   "devDependencies": {
-    "@progress/wct-a11y-spec": "^2.18.0",
+    "@progress/wct-a11y-spec": "^2.19.0",
     "gulp": "^4.0.2",
     "gulp-json-editor": "^2.5.6",
     "gulp-rename": "^2.0.0",