Add PostGIS 3.2 support

[SQUIDwarrior]

I know the documentation says only versions 2.5.2+, 2.4.7+, 2.3.9+ but I wanted to build with 3.2.4. When building with the -PpostgisVersion=3.2.4 flag, my build is failing with the following error:

configure: error: unable to find protobuf-c/protobuf-c.h using CPPFLAGS. You can disable MVT and Geobuf support using --without-protobuf

After doing some digging, it appears the following libraries are missing from the Docker image: protobuf-c-compiler libprotobuf-c-dev libprotobuf-dev. Adding these to the apt-get install and apk add lines in the build-postgres-debian.sh and build-postgres-alpine.sh seem to resolve this issue. I am able to successfully build PostGIS 3.2.4 with these changes.

[SQUIDwarrior]

Oh, just saw there's a PR for this: #68

[tomix26]

The documentation says it because nobody has upgraded it yet 😀. The initial support for PostGIS was contributed by the community, and I'm not actively maintaining it. If you submit a pull request, I'll be happy to merge it into the master branch.

The existing PR #68 lacks a description, and as @kornholi pointed out, the proposed change might not work correctly due to the missing copying of libraries. I haven't really taken a closer look into it.