Use `gradle.properties` for library version for maven release.

[hossain-khan]

As suggested in https://github.com/hossain-khan/json5-kotlin/blob/main/.github/workflows/publish-github-packages.yml#L49-L53

      # The current version is hardcoded in lib/build.gradle.kts as "1.0.0"
      # For dynamic versioning, consider:
      # 1. Using the git tag (${GITHUB_REF#refs/tags/})
      # 2. Reading version from gradle.properties
      # 3. Using a gradle plugin like 'axion-release-plugin'

I want to go with option 2 - Reading version from gradle.properties. Make necessary changes in gradle and publish-github-packages.yml workflow file so that version is read from properties.

Remove those suggestions after done.