[3.10] bpo-45183: don't raise an exception when calling zipimport.zipimporter.find_sp...

[3.10] bpo-45183: don't raise an exception when calling zipimport.zipimporter.find_spec() when the zip file is missing and the internal cache has been reset (GH-28435) (#28438)

This can occur when the zip file gets deleted, you call zipimport.zipimporter.invalidate_cache(), and then try to use zipimport.zipimporter.find_spec() (i.e. you left the zip file path on sys.path).
(cherry picked from commit 209b7035f714dcc41df054b0b023e0b955d7e1a2)

Co-authored-by: Brett Cannon <brett@python.org>