self.q = nn.Linear(embed_size, embed_size, bias = False)
       self.k = nn.Linear(embed_size, embed_size, bias = False)
       self.v = nn.Linear(embed_size, embed_size, bias = False)

Try

       self.qkv = nn.Linear(embed_size, 3*embed_size, bias = False)

    def forward(...):
       ...
       qkv = self.qkv(x)