refactor: make set_credentials synchronous in InMemoryContextCredentialStore - #1116

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: getunlatch/jscpd-github-action@6a212fbe5906f6863ef327a067f970d0560b8c4a. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

src/a2a/utils/signing.py:78:46: unused-ignore-comment: Unused `ty: ignore` directive help: Remove the unused suppression comment

src/a2a/client/transports/__init__.py:11:27: unused-type-ignore-comment: Unused blanket `type: ignore` directive help: Remove the unused suppression comment

src/a2a/client/client_factory.py:47:33: unused-type-ignore-comment: Unused blanket `type: ignore` directive help: Remove the unused suppression comment

src/a2a/client/client_factory.py:41:27: unused-type-ignore-comment: Unused blanket `type: ignore` directive help: Remove the unused suppression comment

repository contains 33 duplications. 2 duplications were part of this PR and were annotated

see src/a2a/client/transports/jsonrpc.py (12-38)