README: add badges - #7

Coverage upload failed: Coverage upload failed (HTTP 404): Not Found. To treat upload errors as warnings, add 'fail-on-error: false' to the action inputs. See https://docs.github.com/en/code-security/how-tos/maintain-quality-code/set-up-code-coverage for more information.

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-python@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Failed to send status report: HTTP Error 404: Not Found

Failed to send status report: HTTP Error 404: Not Found