Fix CI: use new nginx and postgis actions

[nyurik]

I recently released a new nginx github action that should work on all OS and in all runners. Also, postgis action has been updated.

[nyurik]

This fixed a lot of CI issues, but apparently something new is there on macOS-latest. I will merge this regardless as it still improves overall CI health, and will deal with macOS separatelly.

dyld[12895]: Library not loaded: /usr/local/opt/freetype/lib/libfreetype.6.dylib
  Referenced from: <6F45087B-9511-3676-8E75-D8901573A921> /Users/runner/work/martin/martin/target/martin
  Reason: tried: '/usr/local/opt/freetype/lib/libfreetype.6.dylib' (no such file), '/System/Volumes/Preboot/Cryptexes/OS/usr/local/opt/freetype/lib/libfreetype.6.dylib' (no such file), '/usr/local/opt/freetype/lib/libfreetype.6.dylib' (no such file), '/usr/local/lib/libfreetype.6.dylib' (no such file), '/usr/lib/libfreetype.6.dylib' (no such file, not in dyld cache)