Update emsdk.bat after recent python update (#1010)

Fixes: #1009

Author: sbc100

emsdk.bat

@@ -14,6 +14,13 @@ if exist "%~dp0python\3.9.2-1_64bit\python.exe" (
   goto end
 )
 
+if exist "%~dp0python\3.9.2-nuget_64bit\python.exe" (
+  set EMSDK_PY="%~dp0python\3.9.2-nuget_64bit\python.exe"
+  set PYTHONHOME=
+  set PYTHONPATH=
+  goto end
+)
+
 if exist "%~dp0python\3.7.4-pywin32_64bit\python.exe" (
   set EMSDK_PY="%~dp0python\3.7.4-pywin32_64bit\python.exe"
   set PYTHONHOME=