Releases in NppWrapper always needed

In the case of a sync Scintilla callback making N++ calls, the GIL needs
to be released before calling N++, otherwise main thread could be sat waiting
for the GIL, and can't process normal calls, even if they're just "get" calls.

Reported by skrell - https://sourceforge.net/p/npppythonscript/discussion/1188886/thread/55cce926/?limit=25#a167