PostgreSQL latest Support and CI/CD Enhancements

[ruxwez]

This pull request introduces several improvements to our build and testing workflows, as well as enhancements to version detection in the application code. The main changes are focused on supporting the latest PostgreSQL version tag in our Docker and CI pipelines, improving build matrix reporting, and making the application automatically detect the installed PostgreSQL version if latest is specified.

CI/CD and Docker workflow improvements:

• Added latest to the postgres_version matrix in both .github/workflows/docker-build.yml and .github/workflows/pr-test.yml, ensuring our builds and tests always include the most recent PostgreSQL version. [1] [2]
• Changed the default POSTGRES_VERSION in the Dockerfile from 17.5 to latest, aligning the development environment with the updated matrix.
• Restricted the build matrix to only linux/amd64 for PR tests, simplifying the build process and reducing resource usage.
• Improved the PR test workflow by adding a summary job (build-complete) that aggregates build results and provides clearer feedback on build status.
• Updated permissions and concurrency group naming in the PR test workflow for better security and traceability.

Application improvements:

• Enhanced version handling in src/main.rs so that if the user specifies latest as the PostgreSQL version, the application will detect the actual installed version from the postgres binary and use it.
• Added a new utility function run_output in src/common.rs to execute shell commands and capture their output, supporting the improved version detection logic. [1] [2]