In some places 1.26.0 is not available.

Author: rcurtin

build_mlpack.bat

@@ -4,7 +4,7 @@ pip install cython delvewheel wheel setuptools
 rem Pandas 2.1.0 and newer aren't supported on Win32 anymore, so we use an old
 rem version.  We also need to use numpy 1.x, but not too new because that will
 rem require a version of gcc that we won't have.
-if "%WIN_ARCH%" == "Win32" pip install "numpy==1.26.0" "pandas==%PANDAS_VER%"
+if "%WIN_ARCH%" == "Win32" pip install "numpy==1.25.0" "pandas==%PANDAS_VER%"
 if not "%WIN_ARCH%" == "Win32" pip install numpy pandas
 
 python -c "import pandas; print(pandas.__version__)"