DOC: Warning message now tells the required version of Python is 3.8

Packaging/Files/setup_python.sh

@@ -69,7 +69,7 @@ else # case where user provides an OTB_PYTHON_EXE
   if [ ! "$python_major_version" -eq 3 ] || [ ! "$python_minor_version" -eq 5 ]
     then
     printf %s\\n "*****Warning******"
-    printf %s\\n "OTB python bindings normally require python3.5."
+    printf %s\\n "OTB python bindings normally require python3.8 (or 3.7 for windows users)."
     printf %s\\n "The version of OTB_PYTHON_EXE ($OTB_PYTHON_EXE) is \
                   $python_version."
     printf %s\\n "This case is undefined unless you are sure the packages were \