feat: support cohere (close #195)

relay/constant/api_type.go

@@ -19,6 +19,7 @@ const (
 	APITypeOllama
 	APITypePerplexity
 	APITypeAws
+	APITypeCohere
 
 	APITypeDummy // this one is only for count, do not add any channel after this
 )
@@ -52,6 +53,8 @@ func ChannelType2APIType(channelType int) int {
 		apiType = APITypePerplexity
 	case common.ChannelTypeAws:
 		apiType = APITypeAws
+	case common.ChannelTypeCohere:
+		apiType = APITypeCohere
 	}
 	return apiType
 }