Adding "longrope" for Phi-3 (#2172) (#2179)

Adding "longrope" for phi-3

server/text_generation_server/layers/rotary.py

@@ -110,7 +110,7 @@ def static(cls, config, dim, base, device):
                     beta_fast=32,
                     beta_slow=1,
                 )
-            elif rope_scaling["type"] == "su":
+            elif rope_scaling["type"] in ["su", "longrope"]:
                 short_factor = torch.tensor(
                     rope_scaling["short_factor"], dtype=torch.float32, device=device
                 )