chore(release): bump version to v0.45.4

[jeanscherf]

Disclaimer: Do not include SAP-internal or customer-specific information in this PR (e.g. internal system URLs, customer names, tenant IDs, or confidential configurations). This is a public repository.

Description

Bumps version to 0.45.4 to release the protobuf compatibility fix from #285.

Related Issue

Closes #266

Type of Change

• Dependency update
• Bug fix (non-breaking change that fixes an issue)

How to Test

1. Install both sap-cloud-sdk and a2a-sdk==1.1.2 in a project: uv add sap-cloud-sdk a2a-sdk==1.1.2
2. Verify uv lock resolves successfully (picks protobuf in the >=5.29.5,<7 range)
3. Confirm protobuf resolves to a 6.x version when a2a-sdk is present

Checklist

• I have read the Contributing Guidelines
• I have verified that my changes solve the issue
• All tests pass locally
• My code does not contain sensitive information (credentials, tokens, etc.)
• I have followed Conventional Commits for commit messages

Additional Notes

The actual fix (protobuf>=5.29.5, protovalidate>=0.14.1) was merged in #285. This PR is the version bump to cut the release.