Run test-and-lint on PRs targeting next (#95)

Mirrors inorbit-ai/inorbit-connector-python#74 so the next branch gets
the same pre-merge gate as main.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: b-Tomas

.github/workflows/test-and-lint.yml

@@ -4,6 +4,7 @@ on:
   pull_request:
     branches:
       - main
+      - next
 
 jobs:
   lint-and-test: