Oracle Database Doc MCP Server - update Docker image build

[gvenzl]

Description

This PR changes the Docker image build so that it does not rely on third-party actions that are disabled in this repository.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Successfully built in repo clone github.com/gvenzl/mcp

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules