Fix stdlib stubtest flakes (#14886)

Author: AlexWaygood

stdlib/@tests/stubtest_allowlists/darwin-py313.txt

@@ -3,3 +3,10 @@
 # =======
 
 (mmap.MAP_32BIT)?  # Exists locally on MacOS but not on GitHub
+
+# ================
+# Unclear problems
+# ================
+
+# Added in 3.11.1, flagged by stubtest on Python < 3.14 for unknown reasons
+errno.ENOTCAPABLE

stdlib/@tests/stubtest_allowlists/linux-py39.txt

@@ -6,11 +6,11 @@
 # while being inspected by stubtest. Fixed in Python 3.10.
 select.epoll.register
 
-# According to stubtest, these are not present at runtime, starting with
-# Python 3.9.24. Which is not true.
-_frozen_importlib_external.PathFinder.find_distributions
-importlib._bootstrap_external.PathFinder.find_distributions
-importlib.machinery.PathFinder.find_distributions
+# According to stubtest, these are sometimes not present at runtime, starting
+# with Python 3.9.24. Which is not true.
+(_frozen_importlib_external.PathFinder.find_distributions)?
+(importlib._bootstrap_external.PathFinder.find_distributions)?
+(importlib.machinery.PathFinder.find_distributions)?
 
 
 # =============================================================