1. Update Dockerfile to install PostGIS dependencies and PostGIS extension
2. Modify timescaledb-bitnami-entrypoint.sh to include PostGIS in the shared preload libraries list

1. Add smoke tests to the GitHub Actions workflow to verify the functionality of the PostGIS extension.
2. This includes creating the PostGIS extension, checking its version, and testing basic geometry functions.

… process

1. Implement ARGs for POSTGIS_VERSION and POSTGIS_SHA256 to support different PostGIS versions
2. Conditionally set environment variables GEOS_ALPINE_VER, GDAL_ALPINE_VER, and PROJ_ALPINE_VER based on the selected PostGIS version
3. Add Alpine repositories for required packages when using PostGIS 2.x
4. Streamline the build process by combining RUN instructions
5. Update COPY instructions for initdb-postgis.sh and update-postgis.sh

1. Specify POSTGIS_MAJOR, PG_MAJOR, and POSTGIS_VERSION arguments
2. Update and install necessary dependencies
3. Add PostgreSQL repository and import key
4. Install PostGIS extension with specified versions
5. Clean up apt lists