Python: Allow import of refined variable

However, as illustrated by the `CWE-327-InsecureProtocol` test, this fix
is NOT good enough, since now even the `secure_context` is considered to
be insecure (for both versions). Ouch.

Will fix this in a later commit, since it was only discoverd late on.

python/ql/lib/change-notes/2023-02-17-import-refined-variable.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* Fixed module resolution so we allow imports of definitions that have had an attribute assigned to it, such as `class Foo; Foo.bar = 42`.