Support receiving into memoryview

Python 3.11's asyncio.sslproto implementation
may use a memoryview for the buffer
python/cpython@13c10bf#diff-0ae38bdc337cc724282d20111dc780b8a9c07385c80476cf304d5b3c9ec306ecR431-R432

mocket/mocket.py

@@ -304,7 +304,14 @@ def read(self, buffersize):
         return rv
 
     def recv_into(self, buffer, buffersize=None, flags=None):
-        return buffer.write(self.read(buffersize))
+        if hasattr(buffer, "write"):
+            return buffer.write(self.read(buffersize))
+        else:
+            # buffer is a memoryview
+            data = self.read(buffersize)
+            if data:
+                buffer[: len(data)] = data
+            return len(data)
 
     def recv(self, buffersize, flags=None):
         if Mocket.r_fd and Mocket.w_fd: