chore: configure Dependabot to group React updates (#992)

## Summary
- Configures Dependabot to group `react` and `react-dom` updates into a
single PR
- Prevents version mismatch failures in CI when these packages are
updated separately

## Context
PRs #989 and #990 were created separately for `react` and `react-dom`
updates, causing CI failures due to peer dependency version mismatches.
This configuration ensures both packages are updated together in future
Dependabot PRs.

## Changes
- Added `groups` configuration to `.github/dependabot.yml` for React
packages

Author: yogeshchoudhary147

.github/dependabot.yml

@@ -11,3 +11,8 @@ updates:
     ignore:
       - dependency-name: "*"
         update-types: ["version-update:semver-major"]
+    groups:
+      react:
+        patterns:
+          - "react"
+          - "react-dom"