Deprecate get_uncle* endpoints

[kclowes]

What feature should we add?

Use the DeprecatedMethod class to communicate to users that these methods will be removed in v8.

[eraeldog]

from web3._utils.deprecation import DeprecatedMethod
class DeprecatedMethod:
def init(self, fn, message):
self.fn = fn
self.message = message

def __call__(self, *args, **kwargs):
    import warnings
    warnings.warn(self.message, category=DeprecationWarning, stacklevel=2)
    return self.fn(*args, **kwargs)

class MyLibraryClass:
def _old_method(self):
# actual logic here
print("Running old method...")

old_method = DeprecatedMethod(
    _old_method,
    "The 'old_method' will be removed in v8. Please use 'new_method' instead."
)

def new_method(self):
    print("Running new method.")

usage ex
my_obj = MyLibraryClass()
my_obj.old_method() # Will trigger a deprecation warning
my_obj.new_method() # Preferred method