feat: expose version label in kepler_build_info

[sthaha]

This commit adds a label - version to kepler_exporter_build_info metrics to expose the version of kepler installed on the machine / node.

kepler_exporter_build_info{branch="",goarch="amd64",goos="linux",goversion="go1.21.9",revision="unknown",tags="include_gcs,include_oss,containers_image_openpgp,gssapi,providerless,netgo,osusergo,libbp
f,linux,gpu",version="v0.7.10-30-g1c397ff00b72b-dirty"} 1

Fixes: #1449

[github-actions]

🤖 SeineSailor

Here is a concise summary of the pull request changes:

Summary: This pull request updates the kepler_exporter_build_info metric to expose the version of Kepler, obtained from git describe, and includes version information in the linker flags (LDFLAGS) using github.com/prometheus/common/version.

Key Modifications:

• Adds a new version label to the kepler_exporter_build_info metric.
• Updates LDFLAGS to include version information from github.com/prometheus/common/version.

Impact: This change allows users to obtain the version of Kepler installed on the machine or node, enhancing observability and monitoring capabilities. No changes affect the external interface, behavior, or exported functions.

Observations/Suggestions: The change is well-contained and does not introduce any breaking changes. However, it would be beneficial to consider adding tests to verify the correctness of the version information exposed in the metric. Additionally, documenting the new version label in the metric's documentation would improve discoverability and usability.