fdo#46678: pyuno: fix deadlock in Runtime::any2PyObject()

When calling XUnoTunnel::getSomething(), the function must drop the
CPython GIL to avoid deadlock since there are implementations of
XUnoTunnel that acquire SolarMutex.

Change-Id: I51ffce9bdee9a51c932902e77856f865eae81d2a
(cherry picked from commit 0364d3b7e670bddb49d5132268cf28737c3301c6)
Reviewed-on: https://gerrit.libreoffice.org/11178
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>