fix install_requirements.bat

Author: chinazhangchao

install_requirements.bat

@@ -7,14 +7,8 @@ rem This batch file provides a basic functionality similar to the bash script.
 
 cd /d "%~dp0"
 
-rem Find the names of the python tools to use (replace with your actual python installation)
-if "%PYTHON_EXECUTABLE%"=="" (
-  if "%CONDA_DEFAULT_ENV%"=="" OR "%CONDA_DEFAULT_ENV%"=="base" OR NOT EXIST "python" (
-    set PYTHON_EXECUTABLE=python3
-  ) else (
-    set PYTHON_EXECUTABLE=python
-  )
-)
+rem Under windows it's always python
+set PYTHON_EXECUTABLE=python
 
 "%PYTHON_EXECUTABLE%" install_requirements.py %*