assume python is on path for windows for cqlsh.bat

patch by mstepura reviewed by dbrosius for cassandra-6145

bin/cqlsh.bat

@@ -1,5 +1,30 @@
-@echo off
+@REM
+@REM  Licensed to the Apache Software Foundation (ASF) under one or more
+@REM  contributor license agreements.  See the NOTICE file distributed with
+@REM  this work for additional information regarding copyright ownership.
+@REM  The ASF licenses this file to You under the Apache License, Version 2.0
+@REM  (the "License"); you may not use this file except in compliance with
+@REM  the License.  You may obtain a copy of the License at
+@REM
+@REM      http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM  Unless required by applicable law or agreed to in writing, software
+@REM  distributed under the License is distributed on an "AS IS" BASIS,
+@REM  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@REM  See the License for the specific language governing permissions and
+@REM  limitations under the License.
 
-set DSDIR=%~dp0..
+if "%OS%" == "Windows_NT" setlocal
 
-"%DSDIR%\python\python.exe" "%DSDIR%\apache-cassandra\bin\cqlsh" %*
+python -V >nul 2>&1
+if ERRORLEVEL 1 goto err
+
+python "%~dp0\cqlsh" %*
+goto finally
+
+:err
+echo Can't detect Python version!
+
+:finally
+
+ENDLOCAL