For those folks on windows who want to do http gets and posts directly from your PostgreSQL server, we've made binaries for the http extension for PostgreSQL Windows.
These are designed to work with PostgreSQL EDB windows distributions.
If you have PostGIS already installed, many of these files you will also already have since things like the libcurl and PCRE are also packaged with PostGIS.
PostGIS 3.0.0 is planned for release early next week. In the meantime you will find PostGIS 3.0.0rc1 or rc2 available via yum.postgresql.org, apt.postgresql.org, and EDB Windows 64-bit stackbuilder for PostgreSQL 12.