Use maps instead of dicts in HTTP upload modules

ejabberd currently depends on Erlang/OTP 17.1 or higher, so we can now
use maps.

src/mod_http_upload.erl

@@ -108,7 +108,7 @@
 	 get_url                :: binary(),
 	 service_url            :: binary() | undefined,
 	 thumbnail              :: boolean(),
-	 slots = dict:new()     :: term()}). % dict:dict() requires Erlang 17.
+	 slots = #{}            :: map()}).
 
 -record(media_info,
 	{type   :: binary(),
@@ -676,18 +676,18 @@ create_slot(#state{service_url = ServiceURL},
 -spec add_slot(slot(), pos_integer(), timer:tref(), state()) -> state().
 
 add_slot(Slot, Size, Timer, #state{slots = Slots} = State) ->
-    NewSlots = dict:store(Slot, {Size, Timer}, Slots),
+    NewSlots = maps:put(Slot, {Size, Timer}, Slots),
     State#state{slots = NewSlots}.
 
 -spec get_slot(slot(), state()) -> {ok, {pos_integer(), timer:tref()}} | error.
 
 get_slot(Slot, #state{slots = Slots}) ->
-    dict:find(Slot, Slots).
+    maps:find(Slot, Slots).
 
 -spec del_slot(slot(), state()) -> state().
 
 del_slot(Slot, #state{slots = Slots} = State) ->
-    NewSlots = dict:erase(Slot, Slots),
+    NewSlots = maps:remove(Slot, Slots),
     State#state{slots = NewSlots}.
 
 -spec slot_el(slot() | binary(), state() | binary(), binary()) -> xmlel().

src/mod_http_upload_quota.erl

@@ -62,7 +62,7 @@
 	 access_hard_quota              :: atom(),
 	 max_days                       :: pos_integer() | infinity,
 	 docroot                        :: binary(),
-	 disk_usage = dict:new()        :: term(),
+	 disk_usage = #{}               :: map(),
 	 timers                         :: [timer:tref()]}).
 
 -type state() :: #state{}.
@@ -172,7 +172,7 @@ handle_cast({handle_slot_request, #jid{user = U, server = S} = JID, Path, Size},
 		    _ ->
 			0
 		end,
-    OldSize = case dict:find({U, S}, DiskUsage) of
+    OldSize = case maps:find({U, S}, DiskUsage) of
 		  {ok, Value} ->
 		      Value;
 		  error ->
@@ -202,7 +202,7 @@ handle_cast({handle_slot_request, #jid{user = U, server = S} = JID, Path, Size},
 		      enforce_quota(Path, Size, OldSize, SoftQuota, HardQuota)
 	      end,
     NewDiskUsage = if is_integer(NewSize) ->
-			   dict:store({U, S}, NewSize, DiskUsage);
+			   maps:put({U, S}, NewSize, DiskUsage);
 		      true ->
 			   DiskUsage
 		   end,