Remove more Python 3.8 cruft (#13787)

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

@@ -10,9 +10,9 @@ email.utils.getaddresses
 email.utils.parseaddr
 
 
-# ======
-# <= 3.9
-# ======
+# ========
+# 3.9 only
+# ========
 
 # Added in Python 3.9.14
 sys.set_int_max_str_digits

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

@@ -1,6 +1,6 @@
-# ======
-# <= 3.9
-# ======
+# ========
+# 3.9 only
+# ========
 
 # `eventmask` argument exists at runtime, but is not correctly recognized
 # while being inspected by stubtest. Fixed in Python 3.10.

stdlib/@tests/stubtest_allowlists/py39.txt

@@ -1,8 +1,3 @@
-# ========================
-# New errors in Python 3.9
-# ========================
-
-
 # ========
 # 3.9 only
 # ========
@@ -16,24 +11,7 @@ collections.MappingView.__class_getitem__
 hmac.HMAC.digest_cons
 hmac.HMAC.inner
 hmac.HMAC.outer
-
-
-# ===========
-# 3.9 to 3.10
-# ===========
-
-builtins.float.__setformat__  # Internal method for CPython test suite
-typing._SpecialForm.__mro_entries__  # Exists at runtime, but missing from stubs
-
-
-# ===================================
-# Pre-existing errors from Python 3.8
-# ===================================
-
-
-# ======
-# <= 3.9
-# ======
+xxsubtype  # module missing from the stubs
 
 builtins.input  # Incorrect default value in text signature, fixed in 3.10
 collections.AsyncGenerator.__anext__  # async at runtime, deliberately not in the stub, see #7491
@@ -44,13 +22,13 @@ collections.ByteString  # see comments in py3_common.txt
 collections.Callable
 collections.Mapping.get  # Adding None to the Union messed up mypy
 collections.Sequence.index  # Supporting None in end is not mandatory
-xxsubtype  # module missing from the stubs
 
-
-# =======
+# ===========
 # <= 3.10
-# =======
+# ===========
 
+builtins.float.__setformat__  # Internal method for CPython test suite
+typing._SpecialForm.__mro_entries__  # Exists at runtime, but missing from stubs
 email.contentmanager.typ
 gettext.install  # codeset default value is ['unspecified'] so can't be specified
 gettext.translation  # codeset default value is ['unspecified'] so can't be specified

stdlib/@tests/stubtest_allowlists/win32-py39.txt

@@ -11,9 +11,9 @@ email.utils.getaddresses
 email.utils.parseaddr
 
 
-# ======
-# <= 3.9
-# ======
+# ========
+# 3.9 only
+# ========
 
 # Added in Python 3.9.14
 sys.set_int_max_str_digits