Disable unspecified-encoding for py-version above Python 3.15 (#10800)

(cherry picked from commit de75d30)

Author: MehrazRumman

doc/whatsnew/fragments/10791.false_positive

@@ -0,0 +1,3 @@
+Avoid emitting `unspecified-encoding` (W1514) when `py-version` is 3.15+.
+
+Refs #10791

pylint/checkers/stdlib.py

@@ -580,6 +580,7 @@ class StdlibChecker(DeprecatedMixin, BaseChecker):
             "It is better to specify an encoding when opening documents. "
             "Using the system default implicitly can create problems on other operating systems. "
             "See https://peps.python.org/pep-0597/",
+            {"maxversion": (3, 15)},
         ),
         "W1515": (
             "Leaving functions creating breakpoints in production code is not recommended",

tests/functional/u/unspecified_encoding_py315.py

@@ -0,0 +1,18 @@
+"""No warnings for using open() without specifying an encoding (Python 3.15+)."""
+
+import io
+from pathlib import Path
+
+FILENAME = "foo.bar"
+
+open(FILENAME)
+open(FILENAME, encoding=None)
+io.open(FILENAME)
+io.open(FILENAME, encoding=None)
+
+Path(FILENAME).open()
+Path(FILENAME).open(encoding=None)
+Path(FILENAME).read_text()
+Path(FILENAME).read_text(encoding=None)
+Path(FILENAME).write_text("string")
+Path(FILENAME).write_text("string", encoding=None)

tests/functional/u/unspecified_encoding_py315.rc

@@ -0,0 +1,6 @@
+[MAIN]
+py-version=3.15
+
+[Messages Control]
+disable=all
+enable=unspecified-encoding

tests/functional/u/unspecified_encoding_py38.rc

@@ -0,0 +1,2 @@
+[MAIN]
+py-version=3.8

tests/testutils/data/m/minimal_messages_config.py

@@ -5,6 +5,7 @@
 ``test_minimal_messages_config_excluded_file``.
 """
 
-f = open("foo.txt")  # [consider-using-with, unspecified-encoding]
+f = open("foo.txt")  # [consider-using-with]
+# -1:<3.15: [unspecified-encoding]
 
 print("%d" % 1)  # [consider-using-f-string]