chore(deps): Update crewai[litellm] requirement in /a2a/git_issue_agent

Updates the requirements on [crewai[litellm]](https://github.com/crewAIInc/crewAI) to permit the latest version.
- [Release notes](https://github.com/crewAIInc/crewAI/releases)
- [Commits](crewAIInc/crewAI@1.6.1...1.15.2)

---
updated-dependencies:
- dependency-name: crewai[litellm]
  dependency-version: 1.15.2
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

a2a/git_issue_agent/pyproject.toml

@@ -9,7 +9,7 @@ dependencies = [
     # We use 1.6.1 instead of the latest because
     # crewai requires openai>=2.30.0
     # but litellm requires openai==2.24.0
-    "crewai[litellm]>=1.6.1",
+    "crewai[litellm]>=1.15.2",
     "litellm>=1.91.1",          # Indirect, prevents CVE-2026-42271
     "crewai-tools[mcp]>=1.6.1",
     "urllib3>=2.7.0",   # Indirect; prevents CVE-2025-66418