Add Mergify configuration for automatic PR merging

Configure Mergify to auto-merge PRs after all CI checks pass (unit tests on Python 3.10-3.12, Ruff linting, coverage report) and at least one maintainer approval is received. Also adds conflict notification rule.

Fixes #7

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Signed-off-by: Rohan Devasthale <rdevasth@redhat.com>

Author: rd4398

.mergify.yml

@@ -0,0 +1,34 @@
+pull_request_rules:
+  - name: Automatic merge on approval
+    conditions:
+      - and:
+          - "-draft"
+
+          # Unit tests
+          - check-success=3.10 on ubuntu-latest
+          - check-success=3.11 on ubuntu-latest
+          - check-success=3.12 on ubuntu-latest
+
+          # Linting
+          - check-success=Ruff 3.12 on ubuntu-latest
+
+          # Coverage
+          - check-success=Coverage report
+
+          # At least 1 reviewer from maintainers
+          - and:
+            - "#approved-reviews-by>=1"
+
+    actions:
+      merge:
+        method: merge
+
+  - name: Ping author on conflicts
+    conditions:
+      - "conflict"
+      - "-closed"
+    actions:
+      comment:
+        message: |
+          This pull request has merge conflicts that must be resolved before it can be merged.
+          @{{ author }} please rebase your branch.