Fix stubs and comment for weakref removal

Author: Joao-Dionisio

src/pyscipopt/scip.pxd

@@ -2251,7 +2251,7 @@ cdef class Model:
     cdef int _generated_event_handlers_count
     # store references to Benders subproblem Models for proper cleanup
     cdef _benders_subproblems
-    # store references to plugins to break circular references in __dealloc__
+    # store references to plugins for the Model <-> Plugin reference cycle
     cdef _plugins
     # store iis, if found
     cdef SCIP_IIS* _iis

src/pyscipopt/scip.pyi

@@ -315,6 +315,7 @@ class Event:
 class Eventhdlr:
     model: Incomplete
     name: Incomplete
+    _caught_events: list
     def __init__(self) -> None: ...
     def eventcopy(self) -> Incomplete: ...
     def eventdelete(self) -> Incomplete: ...
@@ -424,6 +425,7 @@ class IIS:
 
 @disjoint_base
 class IISfinder:
+    model: Incomplete
     iis: Incomplete
     def __init__(self) -> None: ...
     def iisfinderexec(self) -> Incomplete: ...