bugfix - Change the fetchChannelList from POST to GET (#844)

Author: vini-desouza

libraries/bot-connector/src/main/java/com/microsoft/bot/connector/rest/RestTeamsOperations.java

@@ -166,7 +166,7 @@ private ServiceResponse<TeamsMeetingParticipant> fetchParticipantDelegate(
     interface TeamsService {
         @Headers({ "Content-Type: application/json; charset=utf-8",
             "x-ms-logging-context: com.microsoft.bot.schema.Teams fetchChannelList" })
-        @POST("v3/teams/{teamId}/conversations")
+        @GET("v3/teams/{teamId}/conversations")
         CompletableFuture<Response<ResponseBody>> fetchChannelList(
             @Path("teamId") String teamId,
             @Header("accept-language") String acceptLanguage,