fix: use semver version scheme for cz bump

[nikosxenakis]

Description

• Adds --version-scheme semver flag to both cz bump commands in the bump-version action
• Ensures commitizen uses the semver versioning scheme explicitly rather than relying on the default

Test plan

• Verify the bump-version action correctly computes the next version using semver
• Test with prerelease and major-version-zero flags to ensure compatibility