fix: return 422 for invalid historyLength in REST get_task#741

azilbersteinSFDC wants to merge 3 commits intoa2aproject:1.0-deva2aproject/a2a-python:1.0-devfrom

azilbersteinSFDC:fix/invalid-history-lengthazilbersteinSFDC/a2a-python:fix/invalid-history-lengthCopy head branch name to clipboard