Add pyperclip stubs

stubs/pyperclip/@tests/stubtest_allowlist.txt

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+pyperclip.__main__

stubs/pyperclip/METADATA.toml

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+version = "1.9.*"
+upstream_repository = "https://github.com/asweigart/pyperclip"
+
+[tool.stubtest]
+platforms = ["win32", "linux", "darwin"]
+apt_dependencies = ["xclip"]

stubs/pyperclip/pyperclip/__init__.pyi

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+__all__ = ["copy", "paste", "set_clipboard", "determine_clipboard"]
+
+from collections.abc import Callable
+from typing import Literal
+from typing_extensions import TypeAlias
+
+class PyperclipException(RuntimeError): ...
+
+class PyperclipWindowsException(PyperclipException):
+    def __init__(self, message: str) -> None: ...
+
+class PyperclipTimeoutException(PyperclipException): ...
+
+_ClipboardMechanismName: TypeAlias = Literal[
+    "pbcopy", "pyobjc", "qt", "xclip", "xsel", "wl-clipboard", "klipper", "windows", "no"
+]
+_ClipboardCopyMechanism: TypeAlias = Callable[[str], None]
+_ClipboardPasteMechanism: TypeAlias = Callable[[], str]
+
+def copy(text: str) -> None: ...
+def paste() -> str: ...
+def set_clipboard(clipboard: _ClipboardMechanismName) -> None: ...
+def determine_clipboard() -> tuple[_ClipboardCopyMechanism, _ClipboardPasteMechanism]: ...
+def is_available() -> bool: ...