fix a typo in license_thirdparty_proprietary.txt
fix a typo in license_thirdparty_proprietary.txt

Change PROPIETARY  to PROPRIETARY.
kmosher/PowerShell,bmanikm/PowerShell,bingbing8/PowerShell,daxian-dbw/PowerShell,TravisEz13/PowerShell,bmanikm/PowerShell,kmosher/PowerShell,TravisEz13/PowerShell,bingbing8/PowerShell,PaulHigin/PowerShell,jsoref/PowerShell,bmanikm/PowerShell,jsoref/PowerShell,PaulHigin/PowerShell,KarolKaczmarek/PowerShell,jsoref/PowerShell,bmanikm/PowerShell,bingbing8/PowerShell,TravisEz13/PowerShell,PaulHigin/PowerShell,TravisEz13/PowerShell,bmanikm/PowerShell,JamesWTruher/PowerShell-1,daxian-dbw/PowerShell,bingbing8/PowerShell,jsoref/PowerShell,KarolKaczmarek/PowerShell,jsoref/PowerShell,bingbing8/PowerShell,kmosher/PowerShell,JamesWTruher/PowerShell-1,JamesWTruher/PowerShell-1,PaulHigin/PowerShell,kmosher/PowerShell,kmosher/PowerShell,JamesWTruher/PowerShell-1,KarolKaczmarek/PowerShell,KarolKaczmarek/PowerShell,daxian-dbw/PowerShell,daxian-dbw/PowerShell,KarolKaczmarek/PowerShell