feat: add user-agent to client requests

[runcom]

go-fdo-server also needs this for to0 too

[runcom]

@mmartinv right now, the rpms produced in packit have VERSION=0 cause nothing sets that, I've modified that

[packit-as-a-service]

Failed to load packit config file:

Cannot parse package config. ValidationError({'jobs': {0: {'packages': defaultdict(<class 'dict'>, {'go-fdo-client-fedora': {'value': {'fix-spec-file': ['Unknown field.']}}})}, 1: {'packages': defaultdict(<class 'dict'>, {'go-fdo-client-fedora': {'value': {'fix-spec-file': ['Unknown field.']}}})}, 2: {'packages': defaultdict(<class 'dict'>, {'go-fdo-client-fedora': {'value': {'fix-spec-file': ['Unknown field.']}}})}, 3: {'packages': defaultdict(<class 'dict'>, {'go-fdo-client-centos': {'value': {'fix-spec-file': ['Unknown field.']}}})}, 4: {'packages': defaultdict(<class 'dict'>, {'go-fdo-client-centos': {'value': {'fix-spec-file': ['Unknown field.']}}})}, 5: {'packages': defaultdict(<class 'dict'>, {'go-fdo-client-fedora': {'value': {'fix-spec-file': ['Unknown field.']}}})}, 6: {'packages': defaultdict(<class 'dict'>, {'go-fdo-client-centos': {'value': {'fix-spec-file': ['Unknown field.']}}})}}, 'packages': defaultdict(<class 'dict'>, {'go-fdo-client-fedora': {'value': {'fix-spec-file': ['Unknown field.']}}, 'go-fdo-client-centos': {'value': {'fix-spec-file': ['Unknown field.']}}})})

For more info, please check out the documentation or contact the Packit team. You can also use our CLI command config validate or our pre-commit hooks for validation of the configuration.

[runcom]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds a User-Agent header to outgoing client requests, which is a good feature for server-side logging and client identification. The version is injected at build time. My review has identified a few issues:

• There is a critical error in both the Makefile and the RPM spec file in how the version is injected using linker flags. The path to the version variable is incorrect, which will cause the version to default to 'unknown'.
• The implementation of the http.RoundTripper for adding the user agent can be made more robust to handle cases where a request might have a nil header. I've also suggested a small refactoring to improve code clarity and follow Go idioms.

Please address these points to ensure the feature works correctly and robustly.