gdal: wrap executables in environment containing numpy

Since gdal 3.8.1 there is a numpy dependency on the python library it
seems. This resulted in broken python scrips such as gdal2tiles.py

```
[nix-shell:~/map-scraper/shake-rg]$ gdal2tiles.py --help
ModuleNotFoundError: No module named 'numpy'
```

Therefore it's important to wrap the executables in an environment which
contains numpy.

pkgs/development/libraries/gdal/default.nix

@@ -198,8 +198,9 @@ stdenv.mkDerivation (finalAttrs: {
     ++ darwinDeps
     ++ nonDarwinDeps;
 
+  pythonPath = [ python3.pkgs.numpy ];
   postInstall = ''
-    wrapPythonPrograms
+    wrapPythonProgramsIn "$out/bin" "$out $pythonPath"
   '' + lib.optionalString useJava ''
     cd $out/lib
     ln -s ./jni/libgdalalljni${stdenv.hostPlatform.extensions.sharedLibrary}